Vintage ring origin

[InnaR]

Hi. I'm in the market for an antique/vintage stone. Looking for something truly exquisite (prefere smaller size for a to die for performance). Started with lurking on Ebay for about a month looking for an OMC. Didn't see anything there worth buying. Contacted Adam at OWD, he suggested on a nice stone. But yesterday i was researching archived topics on Pricescope on Vintage Russian diamonds and found out that vintage Russian diamonds considered to be the ones of the best by Pricescopers. I'm of Russian origin by myself, and i noticed a long time ago that tiny Russian diamonds of my older Russian friends sparkle like crazy. I've never seen a Russian diamond bigger than .3-.4 (don't know the reason for that).

I stumbled on a vintage Russian ring. It looks like a fire ball even from the pictures. But since I've never seen a ring like that with a diamond as large as this one, i;m not 100% sure in authenticity of the ring. There are no lab papers.

I would appreciate any opinions on whether this ring and diamond look authentic to Soviet era?

UPD: Forgot to mention that center diamond size is slightly larger than 1.0, It's an I color and SI-2 (eye clean) clarity.