Help identifying this turquoise, please!

[Greatrocks123]

Nice earrings Tate, I have some thoughts to share. 1st it would be extremely rare for someone to make gold and diamond mounts then use average or lesser turquoise in them. So I feel you should expect to find the highest grade turquoise in your set. The lavender pit turquoise from Bisbee has been sought after since the 1890’s but today is considered to have the richest natural color and is highly prized, worthy of gold and diamond settings. the only true way of determining a turquoise is through laboratory chemical analysis compared to a know reference source. Anything else is simply a guess by those who work with the material. I would guess Lavender is a good candidate but there are others to consider
Another turquoise to consider would be Morenci. It has been around just as long as the lavender pit and produced high grade turquoise and a byproduct to its copper industry. Morenci is known for its pyrite inclusions as yours shows-- but it is not the only turquoise to have pyrite inclusions.
Your stone seems to have a slight green patch. I have included a photo of my Morenci it also has pyrites that look silver and there is an area of a green stain around a crack line. Considering its value it is another candidate for high dollar settings.
One thing that causes me concern is the off color patchwork on the back of the stone.
Some explaining…I have included a photo of reconstructed turquoise where pyrites have been

included in the mix. Just for an example…notice how the matrix lines and borders of the stone do not match up. Great indicator that this is a pressed block or reconstructed material. Natural turquoise should have many matching borders like you see in your stones. They fit together like a jigsaw puzzle across the borders. Not all areas of a stone will fit so nicely but there should be some area that will tip you off. Some natural turquoise like Hubei will drive you crazy!
So why the light blue patch on the back? Possibly a filler material for a flaw in the stone. A lot of the turquoise I cut is backed with various materials to level and stabilize the stone for cutting. Most stones I leave the backing on and mount so that you don’t see the back of the stone. Some stones I grind away the backing so I can mount a lighter weight stone or show the back of the stone. This leveling of the back may leave crevices filled with the backing. This may be your case. It doesn’t devalue your stones. Backing has been an industry standard for many years.
My third bet would be a good clear cut of Bisbee…nothing wrong with that !! hope this helps, Kyle