Cultured Pearl and Diamond Necklace and Matching Pair of Earrings

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Origin of Name

The name refers to an extraordinarily beautiful cultured pearl and diamond necklace, made up of a single row of cultured, graduated, spherical, silvery-gray pearls, with a range in size of 15-18.3 mm, falling within the range in size of cultured black Tahitian pearls, that appeared at the Sotheby's "Magnificent Jewels and Noble Jewels" sale, held in Geneva, on May 11, 2010. The necklace and matching pair of earrings were referred to as the property of a gentleman, and characterized as an Important Cultured Pearl and Diamond Necklace, and a Pair of Cultured Pearl and Diamond Earrings. The necklace sold for 194,500 CHF equivalent to US$ 176,500 which was significantly higher than its upper pre-sale estimate. The sale clearly demonstrated that cultured pearl jewelry with extraordinary qualities can sometimes perform equally well or even better than their natural counterparts, at public auctions. A comparison of the sale prices achieved by the two lots, 374 and 392 at the same auction, clearly brings out this fact. Lot 392 is the Cultured Pearl and Diamond Necklace and Matching Pair of Earrings, the subject of this webpage which sold for !94,500 CHF. Lot 374 is the Natural Pearl and Diamond Devant de Corsage, that once belonged to Her Majesty Queen Olga of Greece, with a historical provenance of over 150 years, that sold for only 164,500 CHF (US$ 149,500). In spite of the clear credentials of the Devant de Corsage, such as the natural provenance of the pearls, the noble history of over 150 years associated with it, and the exquisite and perfect design features of the piece, it could not surpass the price achieved by the Cultured Pearl and Diamond Necklace and Matching Pair of Earrings, which sold for 30,000 CHF more than the former, even though the latter had no historical provenance associated with it.

Characteristics of the Cultured Pearl and Diamond Necklace

The Cultured Pearl and Diamond Necklace is an "Opera" under the modern system of classifying pearl necklaces

The necklace consisting of 41 pearls has a length of approximately 725 mm, equivalent to 28.5 inches. Accordingly, in keeping with the modern system of classifying pearl necklaces based on their lengths, the length of 28.5 inches, falls within the category of "Opera" which has a range of 25-34 inches. Thus, the Cultured Pearl and Diamond Necklace is an "Opera" under the modern system of classifying pearl necklaces.

Modern system of classifying pearl necklaces based on length

S/N	Length in inches	Name of necklace
1	10 - 13 ins.	Collar
2	14 - 16 ins.	Choker
3	17 - 20 ins.	Princess
4	21 - 24 ins.	Matinee
5	25 -34 ins.	Opera
6	>35 ins.	Rope

The most striking feature of the cultured pearls in the necklace is their uniform spherical shape and size

The most striking feature of the cultured pearls in the necklace is their apparently uniform spherical shape and size. This is not surprising as a characteristic feature of cultured pearls is their consistently uniform spherical shape and size. This feature is also used in distinguishing cultured pearls from natural pearls, in which the existence of spherical pearls are extremely rare. Thus, putting together a necklace of this type using natural spherical pearls only is a near impossibility. Most of the natural pearl necklaces that one comes across at auctions, is actually an assemblage of not only spherical pearls, but also near-spherical, button-shaped and oval-shaped pearls, in which some of the pearls may show a somewhat baroque outline in spite of their regular shape.

The range in size and arrangement of pearls in the necklace

The cultured pearls in the necklace range in size from a minimum of 15.0 mm to a maximum of 18.3 mm. The pearls in the necklace are said to be graduated, with larger pearls in front, and the pearls gradually decreasing in size towards the rear and the smallest pearls situated towards the clasp. There are 41 pearls in the necklace with an arrangement of 20 - 1 - 20, in which the odd median pearl is at the center, and 20 pearls on either side of it. The 21st pearl counted from any one of the clasps, is the odd median pearl, and the largest pearl in the necklace, whose diameter is 18.3 mm. The smallest pearl of 15 mm is one of the two pearls closest to the clasp. The range in size of 15.0 mm to 18.3 mm, a difference of 3.3 mm, is so narrow, that at a glance all pearls may appear to be of the same size, and one may not be able to perceive the difference in sizes unless actual measurements are made.

Cultured pearl and diamond necklace and matching pair of earrings

Characteristics of the pearls in the necklace

Range in weight of the pearls

The range in size of the pearls are given but not the range in weight. Only the total weight of the necklace, including the clamp and diamonds is given as 274.4 grams. An approximate range in weight of the pearls can be determined using Kunz & Stevenson's conversion table given in Chapter 4 of their publication "The Book of the Pearl" relating size in millimeters to weight in grains of natural pearls, on the assumption that the relative densities of both natural and cultured pearls are equal and the table applies to cultured pearls too. Please refer to the webpage on Nine-Strand Natural Pearl Festoon Necklace for the table. According to this table a pearl of size of 15.0 mm is approximately equal to 90 grains, and a pearl of size 18.3 mm is approximately equal to 150 grains. Thus, the range in weight of the pearls is approximately 90 - 150 grains.

An approximate estimation of the total weight of the pearls using Kunz & Stevenson's conversion table, given in Chapter 4 of the Book of the Pearl

The table can also be used to make an approximate estimation of the total weight of the 43 pearls in the necklace and the pair of earrings, and a comparison made with the given weight.

The range in size of the pearls = 15.0 -18.3 mm

Average of the range in size gives an approximate average of the size of the pearls.

Average of range = 15.0 + 18.3/2 = 33.3/2 = 16.65 mm

According to the table a size of 16.65 mm is approximately equal to 125 grains.

Approximate average weight of each pearl in the necklace and earrings = 125 grains.

Total weight of all 43 pearls = 125 x 43 = 5,375 grains

= 5375/4 = 1343.75 carats

= 1343.75/5 grams

= 268.75 grams

The weight of 268.75 grams agrees very well with the total weight of the necklace and pair of earrings given as 274.4 grams. Thus it appears that Kunz & Stevenson's conversion table for natural pearls applies equally well to cultured pearls too.

Shape of the pearls

Most of the pearls in the necklace appear to be perfectly spherical or near-spherical pearls. This is obviously the case for cultured pearls in which the shape of the pearls are controlled by not only using perfectly spherical bead nuclei, but also turning over of the implanted pearl oysters at regular intervals in order to encourage a uniform deposition of nacre. Thus, cultured pearls are well known for their consistent spherical shapes and sizes, that facilitates the task of putting together pearl strands of matching shapes and sizes.

Color and overtone color of the pearls

The color of the pearls in the necklace is not given in the Sotheby's catalogue, but a clear photograph of the necklace against a white background clearly reveals the color and overtone of the cultured pearls. The pearls appear to be silvery-grey in color, in which grey is the body color of the pearl caused by melanin pigments associated with the conchiolin component of nacre, and silver the overtone color of the pearls, caused by refraction of light as it passes through alternating layers of aragonite and conchiolin, which is also the cause of iridescence. The table below gives the basic body colors of cultured black Tahitian pearls, overtone colors formed and the combination of the two colors, and the special names given to such combinations. The color of the pearls in this necklace and the matching pair of earrings falls under category 10 on the table, and the special name given to such pearls is "Silver."

Combination of body color and overtones in black Tahitian pearls

S/N	Basic body color	Overtone	Combination	Special name
1	gray	yellow	yellowish-gray	Champagne
2	black	purple	purplish-black	Cherry
3	black	blue	bluish-black	Lavender
4	pale gray	-	pale gray	Moon Gray
5	black	green	greenish-black	Peacock-green or black-green
6	black	rainbow of colors	-	Peacock or Rainbow
7	black	reddish-purple	-	Aubergine or Egg plant
8	gray	purple	purple-gray	Pigeon Gray
9	gray	green	greenish-gray	Pistachio
10	gray	silver	silver-gray	Silver
11	black	gold	golden-black	Tahitian Gold

Luster and brilliance of the pearls

The extraordinary luster and brilliance of the pearls as seen in the photograph, is characteristic of black Tahitian cultured pearls, with a nacre of significant thickness. Luster and brilliance of a pearl is caused by the reflection of light from the surface of the pearl and just below the surface of the pearl, and is dependent on the thickness of the nacre. Natural saltwater pearls that are made entirely of nacre have the maximum brilliance among pearls. Among cultured pearls the maximum luster and brilliance are found among South Sea pearls and black Tahitian pearls, the former having a nacre thickness of 2-6 mm and the latter of 2-3 mm, after a cultivation period of 2-3 years.

Surface quality of the pearls

Blemishes in black Tahitian pearls are quite common, but usually less noticeable given the darker color of these pearls. Most of the pearls in this necklace appear to be blemish-free, but only a closer examination of the pearls could reveal the actual surface quality of the pearls. However, it is important to remember that a 100% blemish free pearl does not exist, and even in pearls that are apparently blemish-free under the naked eye, micro-blemishes usually appear under a magnifying glass.

The clasp of the necklace

The clasp of the necklace probably made of platinum or white gold, is designed as a stylized bow, with two wedge-shaped portions and a collar around the point where they meet. The entire clasp is pave-set with small brilliant-cut diamonds. The silver-grey color of the clasp seem to match the silver-grey color of the pearls in the necklace.

Features of the matching pair of earrings

Each of the matching pair of earrings, consists of a large, spherical. silver-grey, cultured pearl, suspended from a surmount, set with three brilliant-cut diamonds. The pearl is suspended from the surmount by a bell-cap arrangement. The diameter of the two pearls used in the earrings are 17.3 mm and 17.4 mm respectively, indicating to what extent the pearls had been matched, before selection for mounting on the earrings. The pearls of the earrings also closely match the pearls in the necklace, in terms of size, shape, color, luster, surface quality etc.

Evidences that confirm the identity of pearls as cultured black Tahitian pearls

There are several lines of evidence that confirm the pearls in this necklace are cultured black Tahitian pearls. Some of these evidences are :-

1) The silver-grey color of the pearls as seen in the photograph, which is one of over 10 combinations of body color and overtones in black Tahitian pearls. Grey is the body color of these pearls and silver the overtone color.

2) The range in size of the pearls from 15 mm to 18.3 mm, which falls within the range in size of cultured black Tahitian pearls. The usual range in size of black Tahitian pearls is from 8 mm to 17 mm. Pearls less than 8 mm in size are rare. The average size of the pearls is 10-12 mm. Sizes from 13 mm to 17 mm are considered very large and are not so common. Sizes greater then 18 mm are very rare and the largest size recorded is 21 mm.

3) The spherical and near-spherical shapes of the pearls, which is also quite rare among cultured black Tahitian pearls, but more common compared to natural pearls.

4) The extraordinary luster and brilliance of the pearls associated with the thick nacre of the pearls, which is usually 2-3 mm thick, after a cultivation period of 2-3 years.

5) Black cultured pearls of the size range 15-18.3 mm are indeed very large pearls and also extremely rare. Larger the size of the pearls greater is their value. The fact that all 43 pearls in the necklace and the matching pair of earrings, are very rare, high-quality, large black pearls, enhances their composite value. Hence the very high price of 194,500 CHF (US$ 176,500) realized by the necklace at the auctions. The fact that such a high price was realized by a cultured pearl necklace, is an indirect evidence indicating that the pearls are either South Sea Pearls or Black Tahitian pearls. Only these two categories of cultured pearls can command such premium prices, whether at an auction or an ordinary sale.

History of the Cultured Pearl and Diamond Necklace

The species of saltwater oyster that produces black cultured pearls

The species of saltwater oyster used in the production of black cultured pearls, is Pinctada margaritifera, commonly known as the black-lipped pearl oyster. The natural geographic range of this species are the tropical and sub-tropical Indo-Pacific waters from the Persian Gulf to the Gulf of California in Mexico, and in the Pacific Ocean from Japan to the Southern Pacific Islands of French Polynesia. The species reaches its greatest abundance in the atoll lagoons of Eastern Polynesia. There are seven different varieties of the species in its wide geographical range, and the variety used for culturing black Tahitian pearls is Pinctada margaritifera cumingi, which is the largest of all the seven varieties, growing to a maximum size of 12 ins (30 cm) in diameter, attaining a weight of up to 5 kg, and with a life expectancy of 30 years. The optimum pearl-productive period of the oyster, is between 3-7 years, when its diameter is between 6-8 ins. (15-20 cm).

Black cultured pearls were first produced in Japan by Kokichi Mikimoto in the 1930s in a pearl farm on Ishigaki Island in Okinawa

Black cultured pearls are produced in the saltwater oyster species Pinctada margaritifera (black-lipped pearl oyster), in which cultured pearls were first produced by Kokichi Mikimoto in the 1930s after he had successfully perfected the techniques of culturing Akoya pearls, following the historic breakthrough in 1916. It was in 1931, that he was able to culture a black pearl for the first time using the black-lipped pearl oyster in a farm on Ishigaki Island in Okinawa. The first cultured pearls from Okinawa, entered the world's pearl markets in the late 1930s.

Black cultured pearls were first produced in the French Polynesian islands in 1965, but attained international popularity only in 1975

The first black Tahitian pearls were successfully cultured in 1965 using Pinctada margaritifera cumingi on two experimental farms in the Tuamotu archipelago, at Hikueru and Bora Bora, by French scientist Jean-Marie Dornard. However, black Tahitian pearls attained popularity only after 1975, when Jean-Claude Brouillet introduced Japanese skills and technology into the culturing process, in his farm on an atoll in South Marutea, which resulted in the production of high-quality black Tahitian pearls, which was well-received in the western pearl markets. Brouillet sold his South Marutea pearl farm to well-known pearl farmer Robert Wan in 1984, who subsequently worked with the Tahitian Government in introducing new regulations not only to control the number of new pearl farms, but also the quality of production. The new regulations that were strictly enforced, apart from other quality requirements, laid down the minimum nacre depth of black Tahitian pearls to be exported from the country at 0.8 mm. Pearls that did not meet the required standards were destroyed and not allowed to leave the country. These measures enhanced the worldwide reputation of Tahitian pearls and prevented the collapse of the industry. Robert Wan is popularly known as the "Father of the Tahitian Pearls."

The possible source of the black cultured pearls in the necklace are either Japan or French Polynesia

Thus, the possible source of the black cultured pearls in this necklace is either Japan or the French Polynesian Islands, whose pearls are known as Tahitian pearls. If the pearls originated in Japan, their period of origin must have been after the late 1930s. If the pearls originated in French Polynesia, their period of origin must have been after 1965.

The Cultured Pearl and Diamond Necklace and Matching Pair of Earrings registers a price significantly higher than the upper pre-sale estimate

The pearl and diamond necklace and matching pair of earrings was lot 392, in the Magnificent Jewels and Noble Jewels sale, held in Geneva, on May 11, 2010, and was characterized as a property of a gentleman, and an Important Cultured Pearl And Diamond Necklace And A Pair of Cultured Pearl And Diamond Earrings. A pre-sale estimate of 128,000 - 160,000 CHF, equivalent to US$ 116,200 - 145,200 was placed on the lot, which was eventually sold for a price even higher than the upper pre-sale estimate, by 30,000 CHF. The final price realized by the necklace was 194,500 CHF, equivalent to 176,500 USD. The significantly higher price realized for the cultured pearl necklace, clearly shows the value attached to cultured South Sea and Black Tahitian pearls, of extraordinary quality, which even surpasses the value of some natural pearls.

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External Links :-

1) Sotheby's Magnificent Jewels and Nobel Jewels Sale, Geneva. May 11, 2010. Lot 392, Important Cultured Pearl and Diamond Necklace and a Pair of Cultured Pearl and Diamond Earrings.

References :-

1) Sotheby's Magnificent Jewels and Nobel Jewels Sale, Geneva. May 11, 2010. Lot 392, Important Cultured Pearl and Diamond Necklace and a Pair of Cultured Pearl and Diamond Earrings. www.sothebys.com

2) Tahitian Pearls - Imperial Pearls, www.pearls.com

3) South Sea Pearls, Tahitian Pearls - Pacific Pearls International. www.pacificpearls.com

4) Tahitian Pearls- A brief description - Knol. www.knol.google.com