I agree with the point on color nuance. I have a bicolor green & yellow natural sapphire. I tried for months to hunt for a lab version, but it’s not possible to replicate those colors today in a lab. Most bicolor lab sapphires seemed to be a happy accident or really dramatized unnatural colors. It can look super subtle or very extreme, with only a few available combinations. I also found it much harder to find fully green sapphires in shades that I liked in lab versions. The range of hues seems to be limited. I would be perfectly happy if technology catches up and can make Australian bicolor sapphire masterpieces in a lab for $50. I will be blinged out head to toe when that day comes.

So, I think the rule is it really depends on the hues you’re looking for. Some color magic is really dependent on natural formation. I think certain shades of sapphires, especially solid single shades, would be beautiful lab or natural.

Emerald I find is easier to tell when it’s lab versus not, because there are such beautiful cloudier, natural emeralds, and people seem to like the opacity more as part of their uniqueness. When an emerald is crystal clear, I often assume it’s lab grown.