Our Pre-Auction Analysis focuses on elements that are hidden from the non-professional 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). The grade 4+ is granted in rare cases and stands for 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 to 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.

Sotheby’s, Geneva Magnificent Jewels, November 15th 2018

Lot #570

2.61 carat fancy vivid blue pear shape, VS2

3.06 carat fancy vivid blue pear shape, VS2

High catalog estimation: $1,773,860 per carat

Unsold – Didn’t reach the minimum

Two vivid blue pear shapes with 73% and 82% depth, respectively. Each has an ...