09 June

Pearls for June
Pearls, the birthstone for June, are the emblem of modesty and purity.

How Pearls are formed
Pearls are formed inside the shell of molluscs as a defence mechanism against a potentially threatening irritant, such as a parasite, inside the shell. The mollusc’s mantle (the protective membrane), irritated by the foreign body, forms a pearl sac of external mantle tissue cells and secretes calcium carbonate to cover the irritant. This secretion process is repeated many times, producing layers of calcium carbonate, thus producing a pearl.
Present day natural pearling is mainly confined to the seas off the Persian Gulf. However, Australia also has one of the world’s last remaining fleets of pearl diving ships.
Cultured pearls follow the same method of calcium carbonate deposition, but commence with human intervention. The oysters are lifted out of the water and one or more mother-of-pearl beads from a donor shell are placed into a recipient shell.
Freshwater pearls come from freshwater mussels, which live in lakes and rivers. Most freshwater cultured pearls sold today come from China. Saltwater pearls grow within pearl oysters which live in oceans. These are usually cultivated in protected lagoons or volcanic islands.
Cultured pearls can be distinguished from natural pearls by X-ray examination, as the internal structure is different.

The value of pearls in jewellery is determined by lustre, roundness, colour, symmetry and lack of surface flaw. All factors being equal, the larger the pearl the more valuable it is.
The largest known pearl was found in the Phillipines, in Puerto Princesa, Palawan Island in the 1930’s. the pearl is 30cm wide, 67cm long, weighs 34kg!!!
The iridescence (rainbow play-of-colour) which pearls display is caused by the overlapping of successive layers. The thinner and more numerous the layers, the finer the lustre. The very best pearls have a metallic lustre.
While white pearls are the most popular, pink, blue, champagne, green and black saltwater pearls can be encountered. Pearls are sometimes bleached to lighten their colour. Pearls can also be dyed yellow, green, blue, brown, pink, purple or black.

Other types of cultured pearls:
Tahitian pearls come from black-lipped oysters, in Tahiti, the Cook Island and Fiji. They are very rarely black, and usually show shades of green, purple, blue, grey, silver or peacock (rainbow coloured).
South Sea are the largest and rarest of cultured pearls. They can be white, silver, pink, gold or cream. These cultured pearls are produced in the coastline of North-Western Australia.
Akoya pearls are produced by a species of small pearl oysters, which are no bigger than 6-8cm. Akoya pearls larger than 10mm in diameter are therefore, very rare. These pearls were the original Japanese cultured pearls.

In Jewellery
Pearls are strung as necklaces and bracelets. They can be set in rings, brooches, earrings, pins, etc. They can be uniform (all the same size) or graduated.

Because pearls are made from calcium carbonate, they are susceptible to a weak acid solution, and can even be dissolved in vinegar. Keep them away from detergents, perfumes, heat, and cosmetics. Regular careful cleaning and restringing are advisable. Clean using water and cotton wool. Dry with a soft cloth.

Collar, sits directly against the throat, 10-13 inches
Pearl chokers, nestle just at the base of the neck, 14-16 inches
Princess length, comes down to the collarbone, 17-19 inches
Matinee length, fall just below the shoulders, 20-24 inches
Opera length, reaches the breastbone, 45 inches
Pearl rope, anything longer than the opera length, 45+ inches

Pearls at O’Reillys

A few pieces from our upcoming Auction of Fine Jewellery, Watches & Silver on June 21st


Lot 78: A CULTURED PEARL NECKLACE; together with a matching bracelet and pair of earrings,

Lot 81: A SAPPHIRE AND PEARL RING, set with diamonds, €600-700


Lot 161: A PAIR OF ANTIQUE PEARL AND DIAMOND DROP EARRINGS, mid 19th century, two natural pearls, with report, mounted with old cut diamonds of approx 0.60ct, €3500-4000



Auction of Fine Jewellery, Watches & Silver on June 21st at 1pm at 126 Francis Street, Dublin 8

Viewing: Sunday 18th June 12pm-4pm, Tuesday 20th June 11am-5pm and morning of sale 10am-12:30pm.

Catalogue online: Friday 9th June