Rare Vintage "Thailand" Sterling Silver "Lime Opal" Thick Spiral Ring (Size 7)

Rare Vintage "Thailand" Sterling Silver "Lime Opal" Thick Spiral Ring (Size 7)! Thai sterling is known for its high silver content, usually ranging between 95% and 99.9% purity! I have spent the last few hours researching this extremely "rare", Lime - greenish yellow Sterling ring!! The ring is genuine Sterling silver and is stamped "925-Thailand." There is another marking that is extremely hard to identify. The stone is definitely 100% genuine! Acid test confirmed genuine Sterling silver. The center cabachon measures approximately (14mmL × 12mmW). Ring measures approximately (1.1") in diameter. The center stone could be any of the following: Madagascar Green Opal/ Lime Green Opal/ Australian Gaspeite/ or Jade. I still can not confirm the exact stone 100%! I feel strongly that this is "Madagascar Opal." Ring weighs (13.377 grams). Please see all of the photos for details. Free thank you gift!》ATTN: WILL BE VIDEO TAPED WHILE PACKAGING & SHIPPING AT POST OFFICE FOR SECURITY (ITEM #792) (MC) (EB)