Our Pre-Auction Analysis focuses on elements that are hidden from the unprofessional eye. As always, we will describe the important visual elements for those who cannot attend the preview. We will discuss characteristics such as Undertone, Color Dispersion, and Inner-Grade (UDI; a detailed explanation appears at the bottom of this article).

We use grades 1, 2, 3, and 4, 1 being the lowest grade. Grade 4+ is granted in rare cases and stands for stones with an exceptional characteristic. Stones that receive a minimum total UDI score of 8, without a remark, are considered to be “Gems” and are mostly suitable for high-end jewelry, collectors and the investment community.

For your convenience, we have added direct links for the GIA reports.

  • All images in this article review were taken with an iPhone 10, no filters were applied.
  • All auction valuations are per carat and in US Dollars.

Christie’s, Geneva Magnificent Jewels, November 13th 2018

Lot #311

18.96 carat Fancy Vivid Pink, cut-cornered rectangular cut, VS1

High catalog estimation: $2,657,463 per carat

Realized Price: $2,631,901 per carat

This is a very large, vivid, pink diamond with a low...