One electronically tested 18KT white gold ladies cast tanzanite and diamond ring. The featured tanzanite is set within a tiered diamond bezel supported by intertwining shoulders, completed by a two and one-half millimeter wide band. Bright polish finish with milgrain detailing. Trademark is UCG. Identified with markings of "18K 750". Containing: One prong set oval modified brilliant cut natural tanzanite, measuring 21.30 x 17.40 x 11.32mm, exact weight 30.19ct., clarity is eye clean, type I, medium dark, moderately strong, bluish violet color, (GIA bV 6/4), cut is good. Transmitting light with no distortion, transparent. GIA Gemological Report attached. Graded loose prior to setting in the GIA Laboratory, Report #2161211925.Tanzanite is a very rare gemstone that is only found in the country of Tanzania. Originally discovered in 1967. Tiffany & Company, named the stone Tanzanite. It is found in the Usumburu Mountains that border the Umba Valley of northern Tanzania. Tanzanite occurs in gray, brown, violet, blue, reddish-purple, & green. The gem is interesting because of its exceptional pleochroism. Rotated in different directions a tanzanite will exhibit multiple changes of color. Tanzanite has a low tolerance to ultrasonic cleaning, and should not be cleaned using this method. Seventy-Eight prong set round brilliant cut diamonds, measuring 1.60 - 1.60 x 0.96mm (depth est.) approximate total weight of 78 Stones = 1.26ct. Graded in the setting. Clarity: SI-1 to I-1 . Color: G - I. Total Weight of Colored Stones 30.19ct. Total Weight of Diamonds 1.26ct. Total Weight of Ring 16.30 grams. AIG Appraised at $82,275.00.