When it comes to some ruby treatments…the glass is not half full - its totally empty! Gems have been treated for centuries, and some of the treatments are commonly accepted in the jewellery trade and by gemmologists. For example, heat treatment in rubies and sapphires improves the transparency of the gem. It’s a permanent treatment, these gems are formed under tremendous heat and pressure in nature, so it a continuation of the heating that occurs in nature. It is rare to find a polished ruby or sapphire that has not had heat treatment. Heat treatment does not alter the makeup of the Stone.
About 10 years ago, rubies with a new form of treatment known as “Lead Glass Filling” came on to the market. This treatment involves taking non-gem quality rubies and filling cavities and fractures in them with lead glass which alters the construction of the stone. Until this treatment was developed, these rubies had no commercial use. This treatment is not accepted by the jewellery trade. The lead glass can make up a substantial portion of the treated stone. The lead glass is unstable, and will deteriorate over time.
The value of Lead Glass Filled rubies are only a small fraction (less than 1%) of those of a heat treated ruby of similar appearance. It is not obligatory to declare this form of treatment, and sometimes it is hidden behind words like "enhanced ruby". This term could include acceptable treatments that do not alter the makeup of the ruby such as heat treatment. However, the First State Auctions gemological team carefully screens each ruby before coming to auction. We will not include Lead Glass Filled rubies in our auctions.
For more information see the GIA video below on Lead Glass Filled Rubies: