Rare Gem Collection


A Unique 10 carat Alexandrite

10 Ct Alexandrite Origin Mystery

Alexandrite origin identification is very difficult. Even the best labs have trouble figuring out an Alexandrite’s origin. Alexandrites from Ceylon, Africa, and Brazil, and other countries, might have colors that support where they come from, but the reality is that labs are not perfect in this determination. 

GIA Alexandrite Origin Samples
Characteristic color-change pairings of alexandrite from different countries. (Source GIA)

One of the rarest Alexandrites we currently have is a 10.08 cts. Natural Oval Shape Alexandrite. This Alexandrite stone of this size is considered exceptional.

Any Alexandrite with good color change over 1 ct is rare. Size is one of 6 characteristics of rarity

10 Ct Alexandrite Daylight
10 Ct Alexandrite Incandescent

Given the GIA Alexandrite Color Change Pairing Diagram, where do you think this 10 carat stone is from? 

According GIA, the difficulty in identifying alexandrite sources comes from the fact that the stone is usually mined as a byproduct of other more common gemstones. Nevertheless, GIA  proceeds with the following steps for alexandrite origin determination:

  1. Is it natural and synthetic? They test it using Fourier-transform infrared spectroscopy (FTIR) and also rule out imitations.
  2. Natural alexandrites are further tested by a small microscopic laser sample called Laser Ablation (for origin analysis)
  3. A Gemologist and senior Gemologist further analyze the standard information including Raman Spectroscopy, microscope analysis and using various lighting to see color
  4. Further testing called:Fourier-transform infrared spectra are collected and Trace element chemistry collect data that is further plotted against know origin samples to further confirm origin determination.

Even though our source told us this Alexandrite came from Tanzania, none of the labs were able to confirm this origin.

1.GIA Origin of 10 Ct Alexandrite 

10 Ct Natural GIA Alexandrite

GIA, which begin identifying origin from alexandrite stones just recently determined the origin to be Sri Lanka. This made our journey to confirm origin a little bit harder, so we decided to use AGL.

  1. AGL Origin of 10 Ct alexandrite
AGL 10 Ct Alexandrite

AGL, which is usually very accurate with origin identification determined the origin to be Madagascar. We mentioned to AGL that the origin we were told was Tanzania, but the lab tends to be reluctant to go against its own analysis of origin. We then proceeded to submit the stone to GRS for origin as well.

  1. GRS Origin of 10 Ct Alexandrite
GRS 10 Ct Alexandrite

GRS, determined the origin to be Brazil. We knew this was not correct. Brazilian Alexandrites have historically been sold at astronomical prices at auctions. So selling this Alexandrite as Brazil would be very unethical. Don’t be surprised if pushy sellers try to get you to buy a stone with one lab report with an exotic origin. This is a huge red flag and must be further explored.

In the past, we have commented that origin does play an important role in valuing gemstones, but it is vital that the decision to pay a premium does not hinge on one lab report.

Even when we used 3 of the most reputable labs, we still did not get an accurate determination of origin. We think it is important to get two labs to agree on an origin for a prospective client to be sure that they know where the Alexandrite came from. While important to have consistent Alexandrite origin reports, the true value of an alexandrite does not lie exclusively with where it is from.

While our 10 ct Alexandrite might have conflicting origin reports, we recognize that the size itself is the most important rarity factor for this particular rare gem. Additionally, the marvelous Alexandrite of Effect further adds to this gem’s value, see for yourself:

This Alexandrite is available for purchase. Please contact us for more information. Or e-mail us at info@theraregem.com with the subject 10 ct Alex.


Red Diamond and Blue Diamond

Time and time again the notion of diamonds being rare has been displaced. There are exceptions to everything. Red diamonds and blue diamonds are amongst the most highly sought collectors items in the world. Their scarcity is unmatched. Most recently, a 12.11 carat fancy intense blue diamond sold for approximately $1.3 Million Per Carat! Sotheby’s Auction House estimates this 1.38 ct Red Diamond to sell for $1.8 to $2.8M USD!

Fancy Blue Diamond Ring- Source: Christie’s
Fancy Red Diamond Ring- Source: Sotheby’s