French Cut Sapphire Stones Glass, Natural or Synthetic? Is Rehab Worthwhile?

[Stone Hunter]

From my reading it seems that synthetic sapphires were invented around 1900 and widely used in jewelry in the 1920s and 1930s. So when we find a ring from that time period how do we decide if the stones are glass, natural or synthetic? Many jewelry stores have testers that can tell the difference between glass and sapphires. But the following questions remain.

Question #1 "How do I figure out if these are these natural or synthetic stones?"
Question #2 "If they are synthetic and that is common for the time period is it worth refurbishing this ring?"
Question #3 "How would you decide if a jeweler is qualified for such a drastic refurbishment?"

White paper towel background. Blue French Cut stones in badly damaged sterling band with engraving.


Here are some of the PS threads I've read on this subject so far.

French Cut Eternity Thread
https://www.pricescope.com/community/threads/french-cut-eternity-thread.192337/

Your French Cut Wedding Bands
https://www.pricescope.com/community/threads/your-french-cut-wedding-bands.157437/

Coup de foudre French cut eternity band -- GREAT photos in this one!
https://www.pricescope.com/community/threads/coup-de-foudre-french-cut-eternity-band.183090/

Stackable rings with French Cut or European Cut Diamonds
https://www.pricescope.com/communit...h-french-cut-or-european-cut-diamonds.200272/

Silly Question Difference between French Cut and Princess Cut
https://www.pricescope.com/community/threads/silly-q-difference-bx-french-cut-and-princess.197052/

 

[Bron357]

Hi, are you sure the metal is silver? From the 20s 30s platinum was the white metal of choice.
As for testing the stones. A jeweller is likely to have Presidum gem tester. This can easily detect glass. However most synthetic sapphires can’t be tested by a Presidum as the material they use is corundum- exact same thermal conductivity. It’s at this point you need a 20x 30x Loupe (magnifying glass). Natural sapphire will have inclusions, synthetics have gas bubbles and some a peculiar curved colour zoning.
Back in the 20s and 30s synthetic gems were considered “special” and were expensive. That’s why it isn’t uncommon to find synthetic sapphires, rubies or the “popular” fake Alexandrite (it was blue purple to purple pink, nothing like a genuine gem) nestled amongst precious metals and diamonds. Generally, back then, the sapphire colour of choice was that lovely velvety Royal blue. So if the gems in your ring aren’t glass, they could be natural. These days of course synthetics come in every colour and hue of the rainbow and the “top” ones are now being created with “natural like” inclusions.
As for rehabbing, the style of the ring doesn’t really lend itself to having the existing stones removed and new ones put in place. If the metal is silver, likely impossible. Silver is almost impossible to “re work” after original casting. Unlike gold which is extremely malleable, silver is brittle. Then of course you have the issue (and expense - French cuts are on of the most expensive cuts) of needing to have 20 or more sapphires precision cut, and for them all to match the same hue and colour.
It’s a beautiful ring, love it and wear it with its imperfections because they are a record of its History (being well worn as it was well loved) and if so inclined, have another one made in the same style.

 

[Stone Hunter]

Hi, are you sure the metal is silver? From the 20s 30s platinum was the white metal of choice.
As for testing the stones. A jeweller is likely to have Presidum gem tester. This can easily detect glass. However most synthetic sapphires can’t be tested by a Presidum as the material they use is corundum- exact same thermal conductivity. It’s at this point you need a 20x 30x Loupe (magnifying glass). Natural sapphire will have inclusions, synthetics have gas bubbles and some a peculiar curved colour zoning.
Back in the 20s and 30s synthetic gems were considered “special” and were expensive. That’s why it isn’t uncommon to find synthetic sapphires, rubies or the “popular” fake Alexandrite (it was blue purple to purple pink, nothing like a genuine gem) nestled amongst precious metals and diamonds. Generally, back then, the sapphire colour of choice was that lovely velvety Royal blue. So if the gems in your ring aren’t glass, they could be natural. These days of course synthetics come in every colour and hue of the rainbow and the “top” ones are now being created with “natural like” inclusions.
As for rehabbing, the style of the ring doesn’t really lend itself to having the existing stones removed and new ones put in place. If the metal is silver, likely impossible. Silver is almost impossible to “re work” after original casting. Unlike gold which is extremely malleable, silver is brittle. Then of course you have the issue (and expense - French cuts are on of the most expensive cuts) of needing to have 20 or more sapphires precision cut, and for them all to match the same hue and colour.
It’s a beautiful ring, love it and wear it with its imperfections because they are a record of its History (being well worn as it was well loved) and if so inclined, have another one made in the same style.

THANKS for your response!!

I believe the ring is silver because it is stamped "STERLING GERMANY" on the inside. I cannot wear it as is because the ring has been damaged. The metal isn't salvageable.

I was thinking of taking the French cut "sapphires" and putting them into a brand new half eternity. But it they are glass I definitely won't do that. If they are old synthetic stones then what? The French cut stones really appeal to me and not many are for sale.

 

[Stone Hunter]

Here are better photos. I've cleaned the ring and taken these shots outside with no flash. Obviously many of the "sapphires" were lost when the band was damaged. So if I do decide to rehabilitate this ring it will become a half eternity.

Damage is visible


Stones are visible

 

[Lisa Loves Shiny]

Hi Stonehunter. I do not know the answers to your questions but wanted to say that David Klass was able to source the natural heat treated blue french cut sapphires in my avatar ring. You might ask him about it. He can also have damaged stones polished - he has done it for me before.