Twinkle Topaz

Topaz is a hard, hard gem, coming in at a whopping 8 out of 10 on the Mohs hardness scale. It has perfect cleavage in one direction (that’s what she said, har har har, no but really, don’t hit your topaz against hard things, it might split in two). And it’s probably the Ron Swanson of gems: it won’t eat bacon, but it’ll cut through baloney, if you know what I mean. But that isn’t why topaz is so interesting. It’s the colors, Jerry! The colors!

Topaz comes in a variety of colors in nature. You’ve got your precious topaz, the birthstone for the month of November, that comes in a brilliant orange. Then you have your imperial topaz, which shimmers with a nice yellow (not to be confused with citrine, a different yellow gem that isn’t as hardy as topaz, or as expensive). Then you’ve got your reds, your pinks, your blues. The thing is that pale or clear topaz is the most common, but it’s the colorful topaz that catches the most eyes and gets the most money.

So people who want to sell topaz have discovered several techniques to creating and enhancing the color of those clear to pale topaz stones. Topaz isn’t like other gems (though to be fair, other gems aren’t like other gems). Unlike stones like peridot, topaz’s color doesn’t come from the chemical composition, and unlike other stones like sapphire, topaz’s color doesn’t come from trace elements. Instead, topaz’s color comes from “color centers,” or imperfections in the crystal lattice (the physical structure of the gem on the molecular level) that change how light passes through the stone. If you can change the color centers, you can change the stone’s color.

Many colors of topaz, uploaded by wikiuser Humanfeather.

There are two ways to do this (and then a bonus third technique that changes nothing ““ I’ll get to that in a second). The first technique is used on more gemstones than just topaz: heat treatment is a relatively simple way to enhance or change gemstone color using nothing more than, you guessed it, heat. Heat treating is a simple concept with some fancy technology to back it up. Carefully calibrated electric furnaces are used to heat up gemstones. Temperatures can be perfectly set to reach the amount of heat needed for a successful heat treatment. For topaz, using heat treatment can enhance blue colors under certain conditions and create rare-in-nature pink topaz.

London Blue Topaz, uploaded by wikiuser Humanfeather

The second color treatment option is a little bit more wild than just applying heat. Blue topaz is very valuable and pretty, but it’s really rare in nature. So what do scientists and gemologists do? Irradiate the hell out of clear or pale topaz stones. Irradiation is typically done by exposing the stone to radiation ““ most blue topaz are created by taking clear or pale topaz and exposing it to radiation in a nuclear reactor. While this results in pretty blue stones, it also results in those same stones being highly radioactive. So most blue topaz has to spend up to about a year in storage before it can be handled by gem cutters, jewelers, and the general public. If you have some blue topaz ““ don’t worry! It only used to be highly radioactive.

The last color treatment doesn’t actually change the stone: gems can be artificially coated with various chemicals and oils to enhance and change the color. Colorless topaz can be coated in such a way to make it sparkle with every color of the rainbow (this type of topaz is called “mystic topaz” ““ there’s no word on whether wearing mystic topaz while eating Mystic pizza will make the ghost of Julia Roberts appear in your bathroom mirror). I could not find a common use picture of a mystic topaz, but if you click this link, it’ll take you to a mystic topaz ring, sold by Amazon.

Topaz is a gorgeous gem, the geological equivalent of Joseph’s dream coat, but, at least in regards to the color, things are not always what they seem.

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