I purchased a 9k ring today at a second hand shop, believing it to be set with an amethyst. Much to my confusion, when I looked at the ring outside it was a sea blue/green colour. I then googled amethyst changing from purple to blue/green and began reading about Alexandrite which I had never before heard of. It is night time here in Aus so I’m unable to capture the colour change to show you, but after watching a video of an Alexandrite colour change it looks identical. I will take it to a jeweller tomorrow to get their opinion. It is a very unique looking ring.