I’ve purchased a stone from a company called Amora Gems. The company is on the west coast. It’s a lab grown stone made out of carbon and silicon. There are several companies making what is called moissanite but they have gotten the green tones out of it and they compare in color to a natural white diamond. They are also cutting them like a fine diamond with an ideal cut. For a fraction of the price.
If you put it into a real engagement semi mount setting no one will be able to tell the difference. I get more complements on this stone then I get on my real diamond.
https://betterthandiamond.com/amora-gem-search.php
The Charles & Colvard patents on Moissanite expired in February two years ago. It was C&C who perfected the pure white Moissanite and sold them for years. Now, with competition, the price is coming down.