Color-changing Gem (Likely Lab Sapphire)! Size 8 Pear Gold-Plated 925 Ring

Large, elegant, pear-cut color-changing purple/magenta gemstone on a size 8 ring! While I’m not a gemologist, this ring was sold to me as lab-created color-change sapphire; I collect lab sapphires and it matches what I expect to see from them. This stone has a particularly vibrant magenta/pink color change under LED lighting, and then softens to a moody smoky lavender in shaded daylight. It measures approximately 16 mm x 9.5 mm, making it approximately 5.5 - 6 carats.   The jewelry marks appear to be UTC (likely for the Ultimate Trading Corporation) and 925 for sterling silver (pictured), which matched what it was sold to me as: gold vermeil over sterling silver. (Vermeil is a thicker gold coating than gold-plated.) It’s very comfortable on my finger, as the wide band tapers into a smaller band on the back of the finger. Looking very closely, I see very slight wear on the bottom side facets only of the table, but I don’t see any scratches or facet wear otherwise. I’m glad to answer any questions, and thank you for looking!