How long has heat treatment been used?

[Ninama]

I was surfing for pink sapphires and found this ring on eBay. It's decribed as Asscher cut, but doesn't look step cut to me. My question is, if it's from a 1910 piece... might it have been heat-treated? Are older stones sometimes treated and reset?

Original estate 1910 Asscher cut bright pink sapphire from an estate complete with raised crown and small table the stone is set in a custom made 18k white gold ring designed and made just for this stone in the Peter Suchy workshop. 32 diamonds approx. total weight .38cts, G, VS. 1 pink Asscher cut sapphire approx. total weight 1.08cts. Stamped 18k. 5.0 grams.

 

[chrono]

That stone is certainly NOT an asscher. It has an octagonal outline but definitely not a step cut. If it is a 1910 piece, it could have been heat treated. There is no mention of heating in the description. Are you looking for an unheated stone?

 

[Ninama]

Date: 12/11/2007 11:46:53 AM
Author: Chrono
That stone is certainly NOT an asscher. It has an octagonal outline but definitely not a step cut. If it is a 1910 piece, it could have been heat treated. There is no mention of heating in the description. Are you looking for an unheated stone?

Thanks, Chrono. I''m not actually shopping - just looking and learning. I get ''set off'' on internet searches by other people''s posts (i.e., "Asscher pink tourmaline ring"). This time I went looking specifically for Assher cut colored stones.

Untreatead seems to appeal to me more, overall - but I know zip about colored stones... maybe heat treatment is no big deal?

 

[chrono]

Heat treatment is an acceptable practice in many gemstones like sapphires, aquas and the like for many years. The collector usually like unheated stones just for bragging rights about rarity. As long as the buyer is aware the stone is heat treated (no other treatment is acceptable except oiling in emeralds), the buyer is certainly going to pay a whole lot less than for a "virgin" stone.

Heating is done to remove undesireable colours in a stone. In aquas, heat can remove the green to bring out the blue. In sapphires, heating can remove some gray and greens and yellows for the desired blue. If left unheated, the colours can look quite uninspiring and thus no one would buy them. However, great looking unheated blues are quite hard to find, and so they are charged quite a good bit more.

 

[CaptAubrey]

It''s not entirely clear when heat treatment of corundum first started, but it was quite rare before the 1960s-70s. If the stone is indeed from 1910, it''s very unlikely to have been heated THEN. (Later, is a different story.)

A good appraiser can examine the stone and tell you if it''s been heated. Heat treatment almost always leaves evidence behind.

 

[Ninama]

Thanks again, Chrono!

ETA - and CaptAubrey

 

[elmo]

I also think it''s fairly common for folks to swap out stones in older pieces, i.e. just because the metalwork is 1910 don''t assume that the stone is original to the piece.

 

[Ninama]

Date: 12/12/2007 1:36:49 PM
Author: elmo
I also think it''s fairly common for folks to swap out stones in older pieces, i.e. just because the metalwork is 1910 don''t assume that the stone is original to the piece.

It seems that the stone is purported to be from 1910... the metalwork is new (made for the stone).