Our Gemstone Standards

Otzera founder Eitan Tashey testing a gemstone on a hydrostatic balance in a library of gemology books, with a refractometer on the desk beside him.
Specific gravity on a hydrostatic balance, with a refractometer close at hand

Clear Information Builds Trust

Every Otzera listing is prepared to help buyers understand what they are considering. Product information may vary according to the nature of the stone, but our goal is consistent: present relevant gemological facts clearly and distinguish observation, expert opinion and independent documentation.

What You Can Expect

  • 01Accurate measurements and carat weight when available
  • 02Clear identification of the gemstone variety
  • 03Known or reasonably determined treatment information
  • 04Geographic origin only when supported or appropriately qualified
  • 05Disclosure of independent laboratory reports when included
  • 06Photographs intended to represent the stone faithfully
  • 07A written explanation of notable strengths, characteristics and limitations
  • 08The Otzera rating when a product is included in the 1–50 system
An Otzera listing for a 0.93 ct Burmese red spinel, with numbered callouts marking the written evaluation, the photographs, weight and measurements, treatment, origin and the GIA laboratory report, and its Otzera 50 seal circled.
On a listing: the 0.93 ct Burmese red spinel

Photography and Color

Gemstones can appear different under changing light sources, viewing environments and display settings. We aim for faithful color representation and will use multiple views when helpful. Even careful photography cannot fully reproduce the appearance of every gemstone in person.

1.17 ct natural color-change garnet appearing violet, face-up on brushed metal.
One light source
The same 1.17 ct garnet appearing purplish pink under warmer light.
Another

The same 1.17 ct color-change garnet — violet in one light, purplish pink in another

1.20 ct Brazilian blue-green tourmaline, face-up. The same tourmaline under a different light. The same tourmaline held in tweezers, face-up. The same tourmaline in profile, held in tweezers.

Four views of one 1.20 ct Brazilian blue-green tourmaline

GIA Identification Report 2245074847 for the 1.17 ct color-change pyrope-spessartine garnet, showing the stone in both of its colors.
GIA Identification Report 2245074847 for the same color-change garnet

Laboratory Reports

An independent laboratory report, when offered, is separate from the Otzera rating and will be described in the product listing. Buyers should review the issuing laboratory, report number and stated conclusions.

Questions Are Welcome

Gemstones reward close attention. If you would like clarification about a listing, its documentation or the basis of an Otzera assessment, contact us before purchasing.

Get in Touch
Eitan Tashey in the gem lab beside a gemological microscope, explaining a gemstone to the camera.