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ask-a-goldsmith · 1 month

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SPOOKY I AM JUMPING FOR JOY THANK YOU SO MUCH FOR ASKING

What is Cubic Zirconia?

Cubic Zirconia (also known as cubics, CZ, and a pain in my ass) is a synthetic material made out of Zirconium Dioxide(ZrO2). Like diamond, it has a cubic crystalline structure- that's where the "cubic" part of the name comes from.

Sidenote - Cubic Zirconia is often confused with Zircon, a naturally occurring crystal used as a diamond simulant in the first half of the 20th century. Zircon has a chemical composition of ZrSi04.

First introduced into the market in the early 1970s, its popularity as a diamond simulant grew rapidly because it was harder, cheaper, and more effective at fooling the eye than previous simulants. It remains the most popular diamond simulant on the market, as it is extremely hard for the untrained(and sometimes even the trained) eye to distinguish.

CZ has a bit of a rough history in the diamond trade - it's been used to fool customers and businesses alike far too many times to count. Many businesses are wary of working with it or outright refuse for fear of customers accusing them of stone-switching.

How does it compare to diamond?

Visually, Cubics are remarkably similar to diamonds. Let's compare and contrast some individual characteristics.

Brilliance(the amount of light returned in a cut stone): Cubics have a slightly lower brilliance than diamonds, but it's not noticeable to the naked eye.

Fire(the number of rainbow flashes seen in a cut stone): Cubics have slightly higher fire than diamonds, but like with brilliance it's not noticeable to the naked eye. Fire is caused by dispersion - the amount a ray of white light will separate into its separate wavelengths when it enters a material. Diamond has a dispersion of 0.044, while cubics have a dispersion of 0.058-0.066.

Refractive index(the speed at which light travels through a material): Cubics have an RI of 2.15-2.18 compared to diamond's 2.42. This is what causes the difference in brilliance - a material's RI sets the maximum angle at which light can enter a material(called the critical angle). A lower RI allows more light to escape the stone if not accounted for in the cut.

Hardness: Hardness is the factor with the most difference - diamonds, with a hardness of 10, are more than twice as hard as Cubic Zirconia(8-8.5) and it shows. Cubics are much more prone to scratching, chipping, and all sorts of other wear-and-tear damage. Fun fact - one of the ways people in the industry tell cubics from diamonds is to scratch them with sandpaper - Diamonds won't scratch, but cubics will. Unfortunately, this is a destructive method, which means it's only used on stones that are okay to destroy(RE: not customer stones).

Sidenote - you may have noticed that I said a 10 was twice as hard as an 8 - strange, right? That's because hardness is measured on the Mohs scale, which is based on relative hardness and isn't remotely linear.

Lustre(the sheen of the surface): Diamonds and cubics are both high lustre material, with diamond's lustre being slightly higher. This is because diamond is harder, which means it can hold a more perfect polish.

Fluorescence: Did you know many diamonds fluoresce? The most common colours are blue and orange, though other colours do rarely appear. Cubics, if they do fluoresce, will often do so in a greenish-yellow or orangish colour.

Specific Gravity(how dense a material is): Cubics have significantly higher specific gravity than diamonds - more than 1.5 times higher, in fact! Diamond has an SG of 3.52, whereas cubics have an SG of 5.8. This means that a cubic the exact same size as a 1 carat diamond would weigh 1.65 carats!

That was a whole lotta information - what does it actually mean, in terms of looking at the stones side-by-side?

Face-up, diamonds and cubics are nearly identical. Cubics will be slightly less sparkly with slightly more colourful flashes, but not by much. Face-down, a cubic will show some read-through - when moving the stone table down across printed lines, you'll be able to see the lines through the stone. A cubic worn in ring will likely have scratches and chips years before a diamond would. A cubic will also weigh more, but we're working on such minuscule scales that nobody except a professional will notice.

Why is it so darn cheap?

Just how darn cheap is it? a 1 carat Cubic costs $20-$30 - comparatively, a 1 carat diamond can go for anywhere from $5,000-$15,000 depending on its quality(note - a 1 carat cubic may be the same weight as a 1 ct diamond, but it will be noticeable smaller - about the size of a 0.60 ct diamond). There are a few reasons, the biggest of which is that Cubic Zirconia is cheap to produce. Cubics also lack the prestige associated with diamonds, something that seems silly but has a real effect on the price. Just take lab-grown diamonds for example - chemically and physically, they're the exact same thing as diamonds. However, they sell for a tenth the price because they're not "natural".

Anyway, yeah! Hope you liked my little "Cubic Zirconia 101", it was a blast to put together! All information was sourced from GIA Diamonds and Diamond Grading 230 and my 6ish years in the industry. If you want information on how to tell diamonds and cubics apart, this post has a section on it. If you want information on how diamond compares to other simulants, this post will do the trick. If you have any more questions, ask away!!!! I am having so much fun answering!!!

In writing my last few posts, I have realized that there is quite a lot of basic(to me) knowledge required to understand most of this stuff. I've done my best to explain as I go, but I think this deserves its own post. So, here we go!

Junior Gemology 101

This post is mostly about diamonds! I am well aware it's called Junior Gemology, but 90% of what I deal with on a day-to-day basis is diamonds. Also, a lot of this applies to coloured stones too, so no need to repeat myself.

What is a diamond, actually?

Diamonds are carbon! That's all there is! Except for inclusions. And coloured diamonds. Those have little bits of other materials in them. And are also a topic for later. I digress. Like always.

Specifically, diamonds are carbon atoms bonded together covalently in a tetrahedral shape. Confusing enough yet? This means that each carbon atom is bonded to 4 other carbon atoms. It's ok if you don't get it, I spent about 3 hours trying to understand diamond structure before things started to make sense. This website has a 3D model of the tetrahedral structure seen in diamonds and is what I used to finally wrap my head around it. The important part is: diamonds are made of carbon atoms connected in a pattern. If the pattern was different, It wouldn't be a diamond! If the carbon was bonded in hexagonal rings, it would be graphite! Same atoms, veeeerrrryyy different result.

What makes diamonds so darn special?

I've told you what a diamond is - so why do people care about this very specific pattern of carbon? The answer is(mostly) that humanity LOVES shiny things, and diamonds are great at being shiny. Why have diamonds become THE shiny thing to have? A combination of some REALLY successful marketing campaigns and some of diamond's unique characteristics. These characteristics include things such as their hardness, brilliance, and fire. I went deeper into these characteristics and what they mean in terms of telling diamonds from other stones in this post, but I'll give you a quick run-down here.

Diamonds are very(and famously) hard. They're a 10 on the Mohs scale, and almost nothing is harder than them. This doesn't mean diamonds are impervious to damage - while they are very hard, diamonds can also be brittle, and a hard smack in the wrong place can chip, crack, or even shatter a diamond. Trust me, I know. I've broken a few by accident.

Brilliance and fire are what give diamonds their characteristic bling. Though they are classified as different things - brilliance being the bright white reflections of light and fire being the rainbow reflections - they're both caused by diamond's Refractive Index. Refractive index(RI) is the measurement of the speed at which light travels through different materials - for our purposes though, think of it as how much a ray of light bends when it moves from one material to another. Diamonds have an RI of 2.42, which causes high brilliance and a medium amount of fire. RI isn't super important for most people to know - it really only comes into the conversation when comparing diamonds to simulant materials.

What are the 4 Cs?

The 4 Cs are the meat and potatoes of diamond basics - Carat weight, Colour, Clarity, and Cut. These four terms are used to describe diamonds worldwide, each describing a different part of a diamond's look.

Carat weight is the weight of a diamond. Pretty self-explanatory. What's not clear is what a carat actually is - no, not a carrot. A carat. A carat is 0.2 grams. Therefore, a 5 carat diamond(good lord) would weigh 1 gram. With me? Why do we weigh diamonds in carats instead of grams like sane people? Because way back yonder, carob seeds were used as a counterweight to weigh diamonds, and language did what language does.

Image from loosegrowndiamond.com

Colour refers to - you guessed it - the colour of the diamond. There are two basic systems that GIA(The Gemological Institute Of America, and the accepted authority of these things in North America) use; the normal colour range and the coloured or fancy diamond range. The normal colour range is used for stones that are colourless, light yellow, or light brown. These are the most common colours of diamond, thus the "normal" colour range. These stones are graded alphabetically D-Z, with D being colourless and Z being quite noticeably yellow or brown. Normal range colour grades are sorted into 5 groups based on the general amount of colour; colourless(DEF), nearly colourless(GHIJ), Faint(KLM), Very Light(N-R), and light(S-Z).

Image from GIA article 4Cs Color

Stones that fall outside this range (stones that are too yellow or brown for the scale or show any colour other than yellow and brown) are graded using the fancy colour grades. Fancy colour grades are an entire thing, but generally pretty self-explanatory. The grade will include 1 or two colours(the more dominant of which goes last) and an intensity descriptor such as light, intense, fancy deep, etc. For example, a stone may be graded as a fancy greyish blue - this means that the stone has a middling amount of colour and is blue with a hint of grey. Easy peasy.

Clarity is how many inclusions are in a stone. Well, technically it's more complicated than that, accounting for placement and contrast and type of inclusion etc etc etc. Really, clarity is how many inclusions you see in a stone. Inclusions are things in the diamond that are not diamond, such as included crystals, or imperfections in the diamond itself, such as cracks(called feathers) or chips.

Clarity grades are, frankly, confusing as fuck. There are 11 grades, broken down into 6 grade groups. From highest to lowest, they are; Flawless, Internally Flawless, Very Very Slightly Included(VVS), Very Slightly Included(VS), Slightly Included(SI), and Included(I). VVS, VS, and SI are each broken into 2 grades - 1 and 2. I is broken down into 3 grades - 1, 2, and 3. The lower the number within a grade, the better the grade - a VS1 stone would be less visibly included than a VS2. You know what'll help? Visuals!!

Images from GIA D&DG Chapter 11. Credit to John Koivula/GIA

The diamond on the left is graded as a VVS2 - the red arrow points to the inclusion that gave it this grade. The diamond on the right is graded as an I2. No red arrows are required - this stone has many highly visible inclusions. If you want a little more info (and examples) of clarity grades, GIA has a lovely little tool that explains it quite well.

Cut refers to the shape of a diamond - specifically, the combination of shape(face-up outline) and cutting style(the arrangement of the facets). A classic round brilliant is what most people think of when they think of a diamond, but there are dozens of different cuts. When talking about cut grade, cut refers to how well executed the cut is. Are the proportions ideal? Is everything symmetrical? Is the polish well done? These determine the cut grade of the stone. Cut grades are as follows, best to worst; Excellent, Very Good, Good, Fair, and Poor.

What are the parts of a cut diamond?

Specifically, the parts of a round brilliant diamond. Round brilliant is the name of the most common cut of diamond. Think of a diamond. Is it round? That's almost definitely a round brilliant. Think I've said round brilliant enough? Round brilliant. Whew. Done with that now. This is best explained with diagrams.

The parts we're most interested in are the table, crown, girdle, and pavilion. The way those 3 parts are shaped and proportioned has a huge effect on the looks and value of a diamond.

Knowledge Check

Let's say you're looking at a 1.01 carat round brilliant diamond - it has a colour grade of F, a clarity grade of SI1, and an excellent cut grade. So, what does this mean to you?

Round brilliant is the cut of the diamond. It has a round outline and a brilliant cutting style. 1.01ct is a fairly large diamond - this one in particular is 6.42 mm in diameter (that's a quarter inch!). This stone is colourless - F is the lowest colour grade in the colourless range, but it is still classified as colourless. The diamond will either have one large or several small inclusions that are easy to see under 10x magnification, but hard or impossible to see while looking through the table of a stone with the naked eye(they may be visible through the pavilion with the naked eye). The diamond will be very well cut - the best cut grade possible, in fact! There will be no visible variation in the girdle outline, and all the facets will be well-placed and symmetrical.

It's up to you to decide if this stone matches your criteria - is SI1 a good enough cut grade for you? Is 1.01ct the right size? How "good" a stone is depends on what you want - there will always be bigger, clearer, more colourless diamonds on the market. What makes a stone "good" is if it's the right fit for you. Another stone may be better quality, but if it's out of your price range, then it's not a good stone for you.

In Conclusion

So, you made it this far! Congrats! Hopefully, I haven't bored you too much. We've really just scratched the surface - this was enough information to give you a good idea of what's going on and allow you to navigate the mysticisms of those strange numbers and letters you see associated with diamonds. All information was taken from the GIA Diamond Essentials 130 and Diamonds and Diamond Grading 230 courses and my 6ish years in the jewelry industry. If you have questions about specific pieces of information or want more resources, send me an ask! I will be delighted to answer.

#tripped a wrote almost 1000 words on cubic zirconia #oops?#not my fault they're really cool #spooky i must thank you again #you are both giving me a reason to talk about fascinating things and helping me study #goldsmith answers #i would have included a photo of the 2 side by side except it would be kinda useless #and all the ones i found online were hella misleading

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ask-a-goldsmith · 1 month

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Junior Gemology 101

What is a diamond, actually?

Diamonds are carbon! That's all there is! Except for inclusions. And coloured diamonds. Those have little bits of other materials in them. And are also a topic for later. I digress. Like always.

What makes diamonds so darn special?

What are the 4 Cs?

Image from loosegrowndiamond.com

Image from GIA article 4Cs Color

Images from GIA D&DG Chapter 11. Credit to John Koivula/GIA

What are the parts of a cut diamond?

The parts we're most interested in are the table, crown, girdle, and pavilion. The way those 3 parts are shaped and proportioned has a huge effect on the looks and value of a diamond.

Knowledge Check

Let's say you're looking at a 1.01 carat round brilliant diamond - it has a colour grade of F, a clarity grade of SI1, and an excellent cut grade. So, what does this mean to you?

In Conclusion

#WOW this on is an absolute beast #final word count is 1674 #fun fact this is how i'm studying for my gemology final #long post #goldsmith answers

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ask-a-goldsmith · 10 months

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Learning about diamond carbon structure

Yall this is what I'm dealing with rn 😭😭

#spent like 10 mind figuring out which lines connect where #had to get a 3d model of it to spin around #smith rambles

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ask-a-goldsmith · 10 months

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Hello my good people - I previously told you about different diamond simulants and their effectiveness in this post. However, I neglected to say anything about how to actually tell diamonds and diamond simulants apart. This post will be focused on how to tell simulants from genuine diamonds, rather than from each other, because that's generally what needs to be done.

I'll be trying to avoid repeating myself as much as possible here because posts about "what makes diamond simulants look like diamonds" and "how to tell diamonds and simulants apart" have quite a bit of overlap. I digress. (I digress a lot. Get used to it.)

First up - glass and plastic. Glass and plastic are made to sparkle, not fool anyone looking close. If a stone has rounded edges, It's plastic. You can also touch the stone to the back of your hand or your lips - if it's room temperature or warm, it's plastic.

Glass is slightly harder to tell, though most glass stones will have chips along the edges of the facets. If there are no chips, check for refractive index differences by looking into the stone through the large, flat top(known as the table). Slowly tilt the stone away from yourself. If you watch carefully, you should be able to see straight through glass stones at some angles. This trick should generally be used with others though - cubics and poorly cut diamonds also show this sometimes.

White sapphires are where it gets hard for amateurs to tell - the differences are mainly in the general look and feel of the stone and may require some practice. White sapphires will have a grayish, almost flat look to them, and no fire(colourful flashes). They will also be cut deeper than most diamonds, but that's near impossible to see in many settings. To check if a stone is a white sapphire, watch it while moving it around - if there are no colourful flashes, and the surface doesn't look like glass or plastic, it's probably a white sapphire.

I will note - these stones hardly ever exist in a vacuum. It's important to look at the quality of the jewelry that they're set in, and the other stones around them when determining if a diamond is genuine.

Cubic zirconias are where you will almost definitely need professional help - these bastards are hard to tell apart from diamonds, especially in settings. And yes, the bastard title is deserved. Several years in this industry has given me Opinions. Anyway. The easiest(non-destructive) way to tell a cubic from a diamond is to flip it upside down and look through the bottom facets, known as the pavilion. You know what? We need a diagram.

This trick is pretty easy with loose stones - take your tweezers, and move the stone(table down) across some printed lines. I usually use business cards, because they're right there and the line size works well. With a genuine diamond, you may see some darkening or a very faint line somewhere in the stone. With cubics, you'll be able to see right through. Generally not to the point of being able to read through it, but you can obviously see the line moving under the stone. ...I say obviously. Take anything I say is clear or obvious with a grain of salt. It's obvious to me, but probably not to the general public. Oops. This trick is MUCH harder with stones set in a ring - which is unfortunate because most stones are set in rings. If you can see the back of the stones, huzzah! You can sometimes do the same trick as with loose stones. If the stone backs aren't visible or the trick isn't working, as far as I know, you're kinda stuck with eyeballing it or the destructive method.

The other way to tell cubics and diamonds apart is to (maybe) destroy them! Yayyy! The grit used in sandpaper is harder than cubics, but softer than diamonds. This means that you can just sand the top of the stone a little, and if it's damaged, whoops! That was a cubic. The downside to this is it destroys the cubic, which usually results in angry people wanting their "diamond" replaced. Sigh.

The final diamond simulant I'll be talking about is moissanite. Moissanites are, as previously mentioned, my preferred diamond simulant. However, they are not the hardest to distinguish. Because of their double refractions, moissanite has a slightly fuzzy look up close. Up close being at like 5-10x magnification, but that's beside the point. You can also check if the stone has a higher-than-normal level of fire, though that needs to be done in comparison to a real diamond and is less effective than just checking for doubling.

There's absolutely no point talking about lab-grown diamonds, as they are actual diamonds. And therefore indistinguishable other than a laser-etched serial number. Some extremely fancy machines can tell the difference, but that is pretty irrelevant to the vast majority of people.

So! I hope I've answered all your(not asked lol) questions. If you have more or want elaboration on anything said here, let me know! I would love to talk about it!

#goldsmith answers #this is mostly a follow up to the first post #bc I realised I said a whooole lot and gave no practical advice #also - the are so much fun to write?? and i learn things too??#best of both worlds #managed to keep this under 1k words this time but barely

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