#bc I realised I said a whooole lot and gave no practical advice

[ask-a-goldsmith]

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!