Is this a natural or synthetic amethyst (2 stones)?

[Alkonost]

Hi guys,
Could you please comment on this amethyst? Is it a synthetic? Some band of breadcrumb inclusions or bubbles? The stone is almost 20 mm long and very clear, except for this one band of some kind of inclusion, and a small scratch I assume? I am fairly sure the isolated blue dots are dust, there were always a couple here and there no matter how hard I tried to get rid of them all.




I am also interested in potentially buying an amethyst cab from GemRockAuctions, here is the link. It doesn't look eye clean but I am a complete newb in this and don't know what type of inclusions these are. Do you think this stone might be natural? Also, what would you suggest as the highest bid for this stone IF you assume it's natural?

16.30CT STUNNING PURPLE INDONESIAN AMETHYST

Amethyst Auctions 19 x 15 x 10mm 16.3 cts Auction #1422792 Gem Rock Auctions

www.gemrockauctions.com

 

[T L]

There’s really no way of telling without a gemologist looking at it with special equipment, but if there’s some zoning, it might be natural. My advice to you is to only purchase amethyst from a reputable vendor who knows their source or cuts their own rough.