The Myth of Princess Di and Yogo Sapphire
by
David
W. Baker
Little Belt
Consulting Services
P.O. Box 906
Monarch, MT 59463
This is a story of advertising hype that has become a kind of modern-day myth. Rural Montana
is a sparsely populated place with long winters. Great Britain is a third of the way around the
world. At such distance it is easy to attribute to the "world" of British Royalty the glitter and
romance of fairy tales. What a marketing tool--plant the idea into the mind of the female
consumer that if she wears a certain piece of jewelry then perhaps a bit of the life of a princess
may rub off on her.
Lady Diana's Engagement Ring
In early 1981 Prince Charles gave Diana Spencer a sapphire engagement ring. Later that year
they were married and Diana became the Princess of Wales. In 1982 Intergem Corporation
greatly expanded the mining, production, and marketing of Yogo sapphire using the trade name,
"Royal American Sapphire." I have a copy of a newspaper article on the Yogo Sapphire Mine.
The photograph above the article is of Princess Diana with the sapphire engagement ring..
Nowhere in the article does it state that the sapphire in Princess Di's engagement ring came from
Yogo Gulch. However, once such an article was published it was only a small step for articles in
other papers and magazines to state that Princess Di's sapphire was a Yogo. The myth grew and
grew. Even today one can find some jewelers suggesting that not only is the sapphire in Princess
Diana's engagement ring a Yogo sapphire, but that Yogo sapphire is in Queen Elizabeth's
engagement ring.
I telephoned several jewelers and gemologists in London who are familiar with Princess Diana's
engagement ring. Johnson, Walker and Tolhurst is the British Company that used to own and operate the Yogo Mine. The sapphire expert at Johnson, Walker and Tolhurst told me that Diana's ring had been in the shop and that he had personally examined it. The other sapphire expert was at Garrard's, the Crown Jewelers which had supplied the 4 trays of sapphire rings from which Diana made her selection. Both said that the sapphire came from Sri Lanka. The most telling comment was, "No, it's not a Yogo sapphire. They are too small."
In fact, most of the Yogo sapphires are small. The crystals grew with the elongated
"barrel-shapes" that are typical for corundum in metamorphic rocks. However, the crystals
formed near the base of the crust of the earth and had to be carried 50 km (or 30 miles) upwards
to (just below) the surface of the earth in a hot magma that was actively dissolving them. The
predominantly flat crystals in the Yogo deposit are the remains of what must have been much
larger elongate crystals at depth. Most of the sapphire was dissolved by the magma, leaving the
many small, flat crystals found in the Yogo dike today.
In contrast, blue sapphire formed in Sri Lanka formed in pegmatites or pegmatite-like bodies as
highly metamorphosed sedimentary rocks (charnockites) underwent partial melting at
mid-crustal depths. Erosion of roughly 20 km of overburden has allowed these rocks to be
exposed at the surface and the placer deposits to form. Large crystals of sapphire are relatively
abundant. However, the crystals tend to be heavily zoned and have abundant inclusions. Most
Sri Lankan sapphire on the market is heat-treated which results in a dramatic improvement in
quality.
From the many photographs of Princess Diana with her sapphire ring, one can estimate the size
of the oval and thus the carat weight of the stone as in the range of 5 to 9 carats. Steve Voynick
on page 163 of the 1995 edition of his book Yogo: The Great American Sapphire gives the weight of the stone as 9 carats. [For many years it was claimed that the largest cut Yogo sapphire
is a flat hexagonal plate in the Smithsonian Museum, weighing 10.2 carats. However, this gemstone came from Sri Lanka, not Yogo Gulch. The museum did not want to offend the donor of
the stone by giving the correct location. The donor has since passed away and it time for the Smithsonian to make the correction official. The largest cut and polished Yogo sapphire that I have been able to verify is just under 4 carats.] Diana's sapphire is larger than any cut Yogo sapphire; however, cut stones this size or larger from Sri Lanka are expensive, but rather common.
According to Richard Hughes on page 105 of his book Ruby & Sapphire, the question is not
whether Lady Diana's sapphire came from Sri Lanka, but whether it was a heat-treated Sri
Lankan sapphire.
Crown Jewels
Steve Voynick (on page 203 of the 1995 edition of his book on Yogo sapphire) states that by
1918 Queen Victoria, Princess Mary, the Duchess of York, and Kaiser Wilhelm of Germany had
some Yogo sapphires in their personal gem collections and that there is a possibility that some
Yogos were included in the jewel collection belonging to the British Crown. The
image here is of some small, loose cut sapphires tucked away in drawers or
jewelry cases. This is a far different image from the spectacular jewels in a
crown worn by royalty to official functions. Which image do you think an advertiser is trying to create when he uses the terms, "Crown
Jewels of England" and "royal history ... of the Yogo sapphire"?
In checking out the myth that British Royalty has Yogo sapphire in their jewelry, I wrote Leslie
Field whose book The Queen's Jewels: The Personal Collection of Elizabeth II is a widely read
reference on royal gemstones. Leslie Field's reply to me is dated October 5, 1998. She stated, "I
am not aware of any Yogo Gulch sapphires set in any piece of jewellery belonging to a member
of the British family."
Value Yogo Sapphire for its own Merits
Most of the Yogo sapphires are small--less than 1 carat. However, the cornflower blue color is
choice. (For example, see the 2.43 carat Yogo that took First Place in the Classic Division.) Lack of zonation and near absence of inclusions means that the stones have outstanding
clarity. When properly cut, this gemstone gives the sensation of pleasureful color. Cornflower blue is the choicest of sapphire color.
In contrast to most sapphire on the market, Yogo sapphire is not heat-treated. It formed at a
depth of 45 to 55 kilometers (or approximately 30 miles), greater than any other commercial
deposit in the world.
Yogo sapphire is a gemstone that Montanans can be justifiably proud of. The demand for these
stones in Montana, particularly for the larger carat sizes, far exceeds production.
Precious
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Last Updated August 12, 2007 by David Baker
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