Many Gemstones are generally enhanced for their color or clarity with a number of different treatments. These treatment are human or machine controlled processes that may or may not involve external elements. All ethical sellers should disclose these treatments clearly when they sell their gems.
There are a few particular treatments to sapphire and ruby which gem buyer should be aware of.
Sapphire and Ruby can be heat treated by the following methods:-
1) Conventional – This is the old furnace heat treatment which is accepted in Gem trade
2) Glass Filled Heat treatment – This is a new treatment where sapphire and ruby is heated with glass filling to enhance the clarity and color. (Mainly on material from Africa. Burmese ruby is not known to be treated in this method). This is an arguable treatment in gem trade.
3) Heat treatment with Beryllium – This is a relatively new treatment where sapphire is heated along with beryllium to enhance the color. (Especially for Yellow and Orange sapphire). This is also an arguable treatment in gem trade (I am seeing a trend that this is is gradually becoming an accepted treatment) Note: Blue Sapphire can also be heat treated with Beryllium..
When seller states that treatment is heated in their product description, you will have to ask them specifically which heat treatment the sapphire or ruby had undergone as prices vary widely. Prices for ruby and sapphire with glass filled heat treatment is relavely low as compared to those that are heated by conventional method. Sapphire and Ruby that are not treated at all will always command a premium price.