Ok, Sue, I've just grabbed a few books and this is what they say but I don't know what years they're from????? Can anybody help?
I think this was from 2006??? Pale pink cover with Amethyst bracelet on front : Guide to Gems and Jewellery Revised & Expanded Edition says ....
p190 - How are some popular gemstones treated? Below are the treatments used for some popular gemstones ..... "Ruby & Sapphire - Heated occasionally with additives. Usually applied this treatment produces, intensifies or lightens colour and/or improves colour uniformity and/or appearance. Examples of the additives used include Beryllium (a light element) to improve colour, Borax or Lead (i.e. glass) to improve appearance.
Then there were 2 books both written by Gavin Linsell, both with red covers. One with a Ruby(?) on the front and the other with a Tanzanite(?) pear cut ring. Both books have the same info on the same page. Bits in bold have been added to the above:
p196/197 - Ruby & Sapphire - Heated and/or the healing of fissures and/or glass filled open fractures and cavities and/or lead glass filled open fractures and cavities and/or dyed and/or bulk diffusion of certain elements during the heating process and/or colourless oil or resin in fissures. Usually applied, these treatments, produces, intensifies or lightens colour and/or improves colours uniformity and/or appearance. Examples of the additives used include Beryllium (i.e. light element) to permanently improve colour and Borax or Lead (i.e. glass) to permanently improve appearances. Normal care. Fillers in voids/cavaities, fissures and/or open fractures can scratch more easily than the host gem or be more vulnerable to damage from heat or some chemicals.
Lastly in the book by Richard W. Hughes which was probably 2008 there is only a generic section on treatments (very basic and doesn't list each gem). However there is a section on Rubies. In it, you have to REALLY understand treatments because it says this ...........
p174 - 3rd paragraph - ......."This [referring to production] tapered off after 1993 but since the advent of high temperature treatment Mong Hsu has become an increasingly important source of Burmese ruby. You can learn more about gemstone treatments in the treatments section of this guide
The problem with that is it is generic and unless you understand treatments (and why would Joe Bloggs?) there is no reason to apply any of the treatments to the section on Rubies.
Hope this helps hun.