The South Sea Pearl Blog / pinctada maxima oyster
January 04, 2022South Sea Pearls with natural color and luster
November 24, 2020
by Dr. L. E. Cartier, first published in Facette 23 (February 2017)
The South Sea pearl oyster Pinctada maxima is known to produce white, cream and golden pearls. Such pearls are cultured mainly in Australia, Burma (Myanmar), Indonesia and the Philippines. Interestingly, 2016 marked the 60th anniversary of the first harvest of South Sea cultured pearls at the Kuri Bay farm (Australia), established by Tokuichi Kuribayashi of Nippo Pearls in 1954 (Müller, 1997). In the past few decades, South Sea cultured pearls have become some of the most desired and expensive cultured pearls in the market.
At present, golden South Sea cultured pearls are harvested mainly in Burma, the Philippines and Indonesia. Pearl farmers have targeted traits and oysters that can enable them to focus on specific nacre colours and thus pearl colours. In February 2016 Dr. Laurent Cartier had the opportunity of visiting Jewelmer pearl farms near Palawan Island in the Philippines and observing the different culturing techniques required to harvest golden South Sea pearls. The Jewelmer company was co-founded in 1979 by Jacques Branellec and Manuel Cojuangco with the aim of producing high-end golden South Sea cultured pearls.
Untreated high-quality golden South Sea cultured pearls from the Pinctada maxima oyster continue to be rare and highly sought after on the international market. This complexity (both ecologically and technically) associated with cultivating these pearls is a limiting factor in offering the market larger quantities of such high-quality cultured pearls. Treatments to attain and imitate such pearl colours and qualities will continue to exist, and SSEF is carrying out research on such treatments. As such, it is also very important to visit production sites and collect reliable samples for research. So it is important that both gemmological research and correct disclosure (see CIBJO Pearl Book) are followed. Another aspect of pearls that SSEF has been very active in is DNA fingerprinting of pearls, such as those from Pinctada maxima. In order to continue to brand and market South Sea cultured pearls from Pinctada maxima as such it is important to be able to distinguish these at a gemmological level, between them and pearls of similar colour from other species. The appreciation of golden South Sea cultured pearls will continue to rise as this relatively new resource in the jewellery industry gains wider attention and embodies a golden future.
For more info also see the article by Cartier & Krzemnicki (2016).
November 01, 2020Colour in cultured pearls has many causes, namely organic pigments and the water reservoir where the pearl shell is grown (sea water or freshwater) that has different manganese (Mn) concentrations with impact on nacre's colours. The mollusc species is, of course, one of the most important factors in this process, specially the donor specimen that provides the mantle tissue that is inserted in the gonads or mantle (depending on the culturing method) of a productive pearl mollusc for the formation of the cultured pearl sac. In Fiji, the local pearl oyster Pinctada margaritifera typica has mantle tissue cells that secrete unusual earthy coloured nacre (seen in the oysters' mother-of-pearl shell interior), and thus the colours of those cultured pearls are also expected to be coloured in such a way. Fiji has been producing natural color beaded cultured pearls, with ocasional non-bead "keshis", in relatively limited numbers since 1999 when Justin Hunter, a biologist and visionary, started his blue economy project with a pearl farm in his home land in Savusavu, Fiji, promoting sustainable luxury through marine cultured pearls. Photos © J. Hunter Pearls Fiji
#pearls #pearljewelry #luxury #gemology #jewelry
February 05, 2020Q:What is a pearl made of?A pearl is a natural gem created by a living organism. When a foreign object is introduced into a mussel or oyster the animal coats the irritant with a substance called nacre, the same material with which it builds it's shell. Layers of nacre build up to make a pearl.
Q:How much time does it take to complete a strand?Strands made of Australian South Sea Pearls up to 15mm are often put together from one harvest. Exceptional strands often take three or more harvests. Some have taken much longer. But the answer is not so simple, because we have been stocking our large pearls for at least the past 10 years to enable us to assemble strands in these sizes. So it is possible that a strand has one pearl from harvest 2004 and another from harvest 1994.
Q:What area in kilometres are the pearl farms spread across?The farms are dotted along more than 2,500 kilometres of coastline – from the Cobourg Peninsula to Exmouth on the north-west Australian coast. An equivalent distance to from London to Moscow! This coastline is in the heart of North Australia’s cyclone belt which annually faces the world’s fiercest tropical storms – a management task in itself to ensure the ongoing viability of the pearl project and the safety of the workers who tend the oysters daily throughout the year.
Q:What year was Australia’s first farm (Kuri Bay) established?Kuri Bay’s history extends to the post-war resurgence of the pearl coast. This remote settlement was founded in 1956, as Australia’s (and, indeed, the world’s) first South Sea pearl farm. Kuri Bay was named for Tokuichi Kuribayashi of Nippo Pearl, the company that provided the technical expertise for this early farming joint venture.
Q:Which order of importance are the 5 virtues of pearl ranked in when pricing a pearl?Lustre, Complexion, Shape, Size, Colour.
Q:What size (age) is an oyster before it can be seeded?Approximately 3-4 years before the first operation.
Q:What months are seeding and harvest done each year?Annually from May to September.
Q:What is the millimetre size of a nucleus?It varies depending on the size and health of the oyster. More important is the nacre thickness. Akoya pearls have a nacre thickness of only around 0.1mm, whereas on a 13mm Australian South Sea pearl the average is 2-4mm.
Q:What is a nucleus made of?The best nucleus is made from 100 per cent hand-selected Mississippi clam shell. Ongoing research provides unequivocal evidence that the Mississippi clam shell produces the best results, sharing the specific gravity and almost identical composition to the nacre of the Australian South Sea pearl, ensuring an end product of the highest quality and durability. It is common for Chinese Freshwater pearls to use a lower grade material, such as plastic, for the nucleus.
Q:How many people are employed in the Australian pearling industry?Approximately 800 employees currently work across the pearl production divisions of the business.
Q:How often are the oysters cleaned?Each oyster is cleaned by hand at least once a month – at slightly shorter periods during the Dry season and longer periods during the Wet season.
Q:How many times can an oyster be seeded?Generally an oyster is seeded only the one time, occasionally twice and rarely a third time.
Q:How long does it take for a pearl to grow?Australian South Sea pearls grow over a 2-3 year period. Other South Sea pearls grow over 1-2 years, and Akoya pearls take only 6 months (on average) to grow.
Q:How big can an oyster grow?Bigger than a dinner plate; approximately 50 years of age.
Q:How durable are Australian South Sea pearls?The durability of all pearls cannot be described as if all pearls are homogenous; e.g. untreated pearls are much more durable than treated pearls (treatments are processes such as dyeing, bleaching and enhancing lustre by chemical treatment).
Akoya pearls are generally the most fragile and least durable of all cultured pearls due to their thin coatings of nacre. Akoya pearls are also almost always treated in some way. As a point of reference, an Akoya is deemed to be good quality if its nacre is 0.15mm thick. Good quality Australian South Sea pearls have on average at least 2mm of nacre. The natural pearl nacre of Australian South Sea pearls will respond well to body oils, etc. Being made primarily of calcium carbonate, it is softer than diamonds and will react adversely to acids which destroy calcium carbonate – as would our teeth.
Q:Why are Australian South Sea cultured pearls so rare?The world’s jewellery market is dominated by gold, silver, and diamonds, with pearls representing only 2% in value of total jewellery sales. Cultured Australian South Sea pearls account for just 1% in volume of the global production of all cultured pearls, yet they account for nearly a third of the value. This obvious preference for quality has increased the demand for high quality pearls worldwide, thus pearls of a certain quality will remain scarce, as increases in production take years in lead times, and quantities cannot be easily or cheaply increased by alternative sources.
While natural Australian South Sea pearls are rarely found in the wild today, cultured pearls are virtually indistinguishable from their natural ancestors.
Q:What gives pearls their shape?Only Nature can decide what shape and colour a pearl will be. While the small nucleus or seed implanted in a pearl oyster is round in shape, due to the thickness of the South Sea oysters’ nacre, the pearls emerge in a wide range of shapes. Symmetry is rare in nature, and therefore round shapes are the most highly valued. See The Five Virtues for an explanation of the variety of Australian South Sea pearl shapes available.
Q:What is a cultured half pearl?Also known as 'mabe' or 'cultured blisters', the cultured half-pearl is initiated by attaching a hemispherical nucleus on the inside lip of the shell. As the oyster grows and secretes its pearl nacre, the half-pearl grows into a domed blister which is later removed from the shell and backed with mother-of-pearl.
Q:What is an Australian South Sea keshi pearl?'Keshi' is a Japanese term which relates to 'small' pearls. They can be either natural or cultured. They can have a solid nucleus (such as a grain of sand), a soft nucleus (such as a small piece of organic material), or a hollow centre, but never an implanted nucleus. As they are impossible to differentiate by eye, all keshi pearls are classified as cultured, unless they are examined by x-ray and accompanied by a certificate from a reputable gemmological laboratory. They generally range in size from 2–10 millimetres and remain quite rare.
Q:What gives a pearl its colour?The colour of South Sea cultured pearls is determined only by nature and can be any of the colours of the mother-of-pearl oyster in which it forms. The finest Australian South Sea pearl oysters can display a magnificent array of all the colours of the rainbow, and as such, Australian South Sea cultured pearls are found in a myriad of colours from golds though to silvers and, of course, white. Pearls may also have many different coloured overtones, which sometimes combine with a translucent lustre to produce the effect known as orient.
Q:What is a South Sea pearl?A South Sea pearl is produced by the Pinctada maxima - the largest of the pearl-producing molluscs. They are mainly produced in Australia, primarily with wild oysters, and in Indonesia and the Philippines with hatchery-reared oysters.