Peridot & Diamonds 18kt White Gold Ring. Â We are offering for sale an exquisite 18kt white gold ladies ring in peridot and diamonds. The ring is set with a trillion cut peridot weighing (2.39cts) and a total of one hundred forty-two round brilliant cut diamonds (0.89cttw). The peridot is eye clean and yellowish/green in color. None of the images of the ring really show the clarity of the peridot, it is very clear. The ring, size 7, was cast and handset. It is in good condition and comes with an appraisal of $3551.00.