Thank you for submitting your item for appraisal. This appears to an 18 karat gold diamond ring with a large 4.25 ct pear shaped diamond plus numerous small white diamonds on the shoulder. According to the information provided the natural drop shaped or pear shaped diamond is of D color and a clarity of vvs1 ( an expert using a 10x loupe can detect flaws only when inspecting the stone from the bottom). Very few comparable pear shaped diamonds of this size and quality have been offered in high end auctions in the past few years. The estimate is based on these few results.