Mirror of Portugal


Weight: 26.07 carats

Dimensions: 17.89 x 16.73 x 10.98 mm

Color: Colorless

Weight of Rough: Unknown

Origin: Golconda, India

Date Found: Unkown

Current Location: Recut into Mazarin III, stolen 1792

*Derived from GemCad modeling.


The Mirror of Portugal (Miroir du Portugal, or MdP) is another one of those famous diamonds where little is known about it, even though it was owned alternatively by the kings of Spain, England, and France. A few portraits and poor line drawings indicate it was a table cut. It was pawned a few times, recut into the Mazarin 3 in the late 1600’s, and then stolen and permanently disappeared in the robbery of the French Crown jewels in 1792. The end. Or so was thought until the FB lead replica was found (see the FB page for this).

Another lead model was found next to that of the French Blue. It is square and correlates to a diamond of about 26 metric carats (below).

Photo by Francois Farges, ©2009

The 1691 French Crown inventory (Brisson, 1787) says the MdP weighed 25 3/8 (old) carats, 26.07 metric carats, and is a square table cut. An exact match to the lead replica.

After further research, it appears that this is in fact the MdP. The lead model must have been made prior to the stone being cut into the Mazarin 3, so that makes it over 300 years old! A GemCad model was created by photogrammetry (outlined in Sucher, 2008) and the CZ replica is shown here. You wouldn’t think it to be a very brilliant diamond based on the photo above showing a simple step cut, but the parallel rows of facets create a house of mirrors effect (below). When looked at from the top down, the reflections appear to go to infinity, with the effect that it looks like the stone itself is about 3’ deep. Stunningly brilliant, outstanding optics, score another one for the ancient cutters over the modern concepts of cutting! It is hoped this research will be printed in an upcoming issue of Gems and Gemology or one of the French publications.

Photoreal image generated using Diamcalc by Octonus (www.octonus.com)

Breaking Update (August 2009)

As it turns out, this particular model, although matching the MdP, may actually be a different diamond called the Portugal diamond.  So don’t draw any conclusions yet!  Come back in 2-3 months when the data should be sorted out.  As with historical diamonds throughout history, their stories change as more information gets unearthed.