What’s the scoop on topaz?

Okay, I’ll admit it: I have a crush on topaz.  This versatile stone is beautiful, durable, and affordable, and it comes in a wide range of lovely blues as well as several other colors.  It has a Mohs hardness of 8 (very hard!) and a high refractive index (sparkle/light reflection).  It does have a relatively strong cleavage, meaning that like a diamond it can be fractured with a sharp blow.  Like any gem, even a diamond, it should not be treated as indestructable, however it is one of the more durable, affordable gemstones on the market.

The only problem is, determining what is and is not topaz and what treatments have been applied can be confusing, given the usual fudging done by the less scrupulous members of the gem industry.  Topaz commonly occurs in clear, golden, and golden pink.  It can also be found in other colors such as pink and light blue, but because topaz is so easily and commonly treated with heat, irradiation, and coatings to produce various shades of blue and pink, it’s safest as a buyer to assume that those colors are not natural and to be very sceptical of anyone who claims otherwise.

So, here you have it: the buyer’s guide to all those topazes! 

White topaz is the natural form most topaz is found in; it’s sparkly, clear, and makes a very affordable diamond substitute, and is normally not treated or enhanced.  Mohs hardness 8.

Golden topaz is naturally occurring as well, and is quite scarce compared to white topaz.  This beautiful champagne colored stone sells for considerably more than white topaz and the various enhanced colors of topaz.  It is sometimes referred to as precious topaz.  When buying golden topaz, use take care to make sure that you are not being sold citrine, a less expensive gem that occurs in some similar colors.  Mohs hardness 8.

Imperial Topaz is the most valuable color.  It is naturally occurring and in order to be considered imperial topaz, it must have both golden tan and pink color tones.  This material is also referred to by some as precious topaz.  Mohs hardness 8.

Sky blue topaz is white or light blue topaz which has been heated and or irradiated to change the color to a light blue.  The color is stable and permanent, and for that reason many sellers do not disclose the fact that this is not a naturally occurring color.  Mohs hardness 8, AGTA treatment code R, H.

Swiss blue topaz is white or light blue topaz which has been heated and or irradiated to change the color to a bright, saturated, cheerful blue.  The color is stable and permanent, and for that reason many sellers do not disclose the fact that this is not a naturally occurring color.  Mohs hardness 8, AGTA treatment code R, H.

London blue topaz is white or light blue topaz which has been heated and or irradiated to change the color to a saturated, deep blue.  This is the darkest blue of the various blue topazes and can make a decent stand-in for blue sapphire, although the difference will be obvious to the educated eye.  The color is stable and permanent, and for that reason many sellers do not disclose the fact that this is not a naturally occurring color.  Mohs hardness 8, AGTA treatment code R, H.

Smoky topaz doesn’t exist!  What some people refer to as smoky topaz is in fact smoky quartz.  Quartz is a less expensive material than topaz.

Yellow topaz doesn’t exist either; this material is in fact citrine, which is a yellow quartz and a very popular gemstone in its own right.

Lemon topaz is another phantom.  It is lemon quartz, which is also known by the more exotic sounding trade name Oro Verde citrine.

Pink topaz is color coated white topaz.  It cannot be re-cut or re-polished without removing the color (unlike the irradiated/heated blue topazes which are have a permanent, stable color throughout the stone), and care should be taken not to damage the coating.  Pink topaz makes a wonderful substitute for pink sapphire, but probably should not be used in wedding or engagement rings due to potential issues with the durability of the coating.  Mohs hardness 8, AGTA treatment code C.

Green topaz is diffusion coated white topaz.  Although the color is permanent, green topaz cannot be re-cut or re-polished without removing the color.  Green topaz is probably the most affordable emerald alternative, although I prefer chrome diopside, a natural, untreated stone, for this purpose.  Mohs hardness 8, AGTA treatment code C.

Ice blue topaz is diffusion coated white topaz.  Although the color is permanent, ice blue topaz cannot be re-cut or re-polished without removing the color, which is a vibrant, ultra-saturated medium blue.  Mohs hardness 8, AGTA treatment code C.

Mystic topaz, rainbow topaz, mercury mist, twilight mystic, and various other trade-named multi-colored topazes are color coated topaz.  They are treated with a process called diffusion.  These coatings can create some spectacular effects; however the buyer simply needs to be aware that the coatings may be damaged over time, especially when they are worn in rings or other jewelry which takes a lot of abuse.  Mohs hardness 8, AGTA treatment code C.

I personally recommend that customers not invest a large sum of money in a piece of coated topaz jewelry.  I tend to steer clear of setting these “novelty” topazes in gold or combining them with more valuable stones.  Showcasing them in a simple sterling silver prong setting will keep your investment down and even allow you to have the stone replaced easily if the coating deteriorates.  No coated topaz should be ultrasonically cleaned or steam cleaned.

So to sum up the various treatments:

White: Natural
Golden: Natural
Imperial: Natural
Precious: Natural
Sky blue: Heated/Irradiated – permanent
Swiss blue: Heated/Irradiated – permanent
London blue: Heated/Irradiated – permanent
Smoky: Is quartz, not topaz
Yellow: Is citrine (a variety of quartz), not topaz
Lemon: Is lemon quartz, AKA Oro Verde citrine
Pink: Coated
Green: Diffusion coated
Ice blue: Diffusion coated
Mystic: Coated
Rainbow: Coated
Others: Coated