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Large & Famous Diamonds - The Portuguese Blue
In response to an enquiry from us:
On a visit to you some (20?) years ago, we viewed the famous blue Hope diamond.
Also on display nearby was another, smaller but more attractive blue diamond. Can you provide us with any information about this other stone, please.
Also do you have an image of it available?
we received the following reply from the Smithsonian Institution:
Your inquiry of August 10, 2005, regarding a diamond has been received in the Smithsonian's Public Inquiry Mail Service for response.
We believe you are referring to the Portuguese Blue Diamond which is the largest diamond in the collection (127.01 carats). Once owned by Peggy Hopkins Joyce, an actress in the Ziegfield Follies, the diamond is on display in the Janet Annenberg Hooker Hall of Geology, Gems and Minerals in the National Museum of Natural History. Despite its name, it has no documented connection with Portugal.
Under ultraviolet light (light with wavelengths shorter than those of visible light), the famous Portuguese Diamond glows bright blue. This phenomenon, called fluorescence, occurs in many diamonds. But the Portuguese Diamond fluoresces so intensely that a hazy blue tinge can be detected in natural daylight as well as artificial light.
Unfortunately, there is no image available.
We appreciate your interest in the Smithsonian Institution.
Blue or White?
According to all previous sources we could find, the Portuguese Diamond was white. The comments from the Smithsonian Institution appear to confirm this, although they refer to it as the Portuguese Blue Diamond because it sounds as though it appears blue even in normal lighting. If you find this confusing, it is important to remember that a diamond's colour refers to its body colour, which can be different from the observed colour depending on lighting conditions and viewing angles.

The Blue Heart
We now believe the blue diamond we originally saw in the Smithsonian was the Blue Heart, also previously known as the Unzue, and incorrectly the Eugenie Blue.

Table of Large Diamonds
RankWeightNameColourShape
40127.01Portuguese BlueWhite; Strong Blue FluorescenceAsscher (Square Cushion)

Coloured Diamonds

Diamond 4C's Tour
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Price v. Quality of a 1 Carat Diamond or
Price v. Quality of a Half Carat Diamond


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