question on tourmaline and citrine

Date: 6/16/2007 3:23:00 PM
Author: Pyramid
It is heated by man, I presume in a lab although I have read with sapphires that a lot used to be heated by man at the mines.

Date: 6/16/2007 3:48:05 PM
Author: riogems
There is nothing controversial about this -- it's when they heat with the presence of other materials that diffuse into the stones and change their colors that it matters. Man has been cooking stones in oven-like apparatus for thousands of years.

Date: 6/16/2007 9:59:12 PM
Author: twodoor2
Heating is a common practice and generally accepted by the trade. It's far less expensive to buy a ruby that is heat treated than one that looks the same, but is unheated. There are some other treatments that are far more controversial, like irradiation, beryllium treatment, coating, laser drilling (to remove inclusions in diamonds), and fracture filling. That's why I refuse to buy emeralds, they are almost ALWAYS treated with fracture filling, and the type of filling can be colored plastic!! After hearing about some of the other horrid forms of adulteration of gemstones, heat treatment seems pretty tame. In fact most paraiba tourmaline that sells for thousands upon thousands of dollars per carat is heat treated. It's worth far more heat treated than not, just like tanzanite (which when not heat treated looks like an ugly brown). With the case of paraiba, there is no guarantee that the untreated stone will turn out to the expected result after cooking, but if it does, megabucks!!


There is natually occurring citrine but it's such an inexpensive gem that to buy heat treated or not really doesn't matter that much. It's when you talk about the big buck stones like rubies, emeralds, sapphires, and diamonds that you have to care more.