Should You Ever Do Scratch Tests On Gems?


Heading to a jewelry store to buy gems is usually the best way to ensure that what you buy is real. However, sometimes you want to double check that the gem is the real thing. A scratch test can identify many authentic gems, but that test, obviously, leaves a permanent mark. With that in mind, the question becomes whether or not you should ever do a scratch test to verify if those gems you got are real.

The Mohs Scale

Gems are rated by hardness using a scale called the Mohs scale. Each level — there are 10 — is represented by a particular gem. More than one gem can have the same Mohs rating, but these 10 gems are just reference points. Diamond, for example, is 10, the hardest rating; quartz is a 7, and the relatively soft fluorite is a 4. For comparison, a drill bit is 8.5 and a copper penny is 3.5. Cubic zirconia, a common diamond substitute, comes in at about 8.5 — not nearly as tough as a real diamond.

Why Do a Scratch Test?

A scratch test has two advantages. One, it's free. You don't have to send the jewelry away or pay an appraiser or grader to verify the stone's authenticity. Two, it's rather good if you know what you're looking for. If that diamond you bought suddenly shows signs of abrasion when you scratch it, then you know you're not looking at a real diamond. By the way, you "scratch" the gem in question with another gem, and then brush away any filings or powder left behind to see if the gem was truly scratched.

The problem with a scratch test is that it is visible and destructive. The scratch will not go away. If you have a real diamond, that might not be an issue because it will be very difficult to scratch the surface unless you try to gouge the stone. But if that diamond turns out to be glass, for example, that glass will have a mark on it.

So, when is a scratch test OK? If the gem you bought is a rough — not a faceted and finished stone but a rough one — you can generally do a scratch test on a protruding point that you think you'll cut off or cover anyway. A faceted stone is often not a good candidate for a scratch test simply due to size. Faceted stones can be a bit more fragile, too. However, if you have a larger stone and think there's an inconspicuous spot -- and you don't mind making a mark — you can certainly try.

If you really want to protect that gem, though, head to a jewelry store. There you'll not only be able to arrange for appraisals, but you'll also be able to buy stones and jewelry that you know are authentic without having to potentially damage the item. Look for someone who provides diamond jewelry in your area to learn more.


29 September 2020

Cleaning My Jewelry

After wearing the same jewelry pieces day after day for years, I realized that a few of my favorite items had developed a significant level of grime. I didn't want to look sloppy, so I started to look into ways to tidy them up. I talked to a friend of mine who knows how to clean everything, and she had some really amazing ideas for cleaning tiny chains and little prongs. This blog is all about the art of cleaning fine jewelry, and even tidying up older costume jewelry pieces. You never know, you might be able to make those older baubles sparkle.