I’d say based on what this stone looks like, it’s normal Amethyst, most likely heat treated of course. Giving dimensions, saying for example it’s 14 x 10mm Oval with estimate of 5mm or so Depth, it’s probably around 4.5 cts. or 4.20 Ct - 4.85 Ct but most likely it’s a standard cut so 4.5 is probably about right. and I’d say medium dark bluish purple, which is common, I fail to see where that red came from, and the only ones that really show up with splashes may be Siberian, but this is definitely not Siberian. so even with that and giving you the benefit to say it’s Eye Clean 1, and good cut, top retail may be around $100.00 but to be perfectly honest, this stuff is as normal as water. and it’s a bit on the dark side so that could also play but as I said, this stuff is as common as water which is why they probably set it in costume jewelry. I’ve seen better color selling on ebay for less than $10.00 if that tells you anything. As a gem dealer, I’d say you’d be lucky to get that out of it.