BUYING TAHITIAN CULTURED PEARLS

Before any Tahitian cultured pearls can be exported, they must comply with basic requirements concerning nacre thickness and quality. The thickness of the nacre results from very slow deposits of successive layers of nacre created by the oyster. Tahiti’s government requires that nacre thickness should be greater than 8 mm. The thickness is directly related to the length of time the pearl oyster spends in the lagoon; this length of time should not be less than 18 months.

The appreciation and understanding of the pearl value is not a easy task as it depends on various criteria:

The rarity
It takes a long time, many technicians and hundred of oysters, which have been cultivated, cleaned, brushed and grafted to obtain a perfect pearl.

The shape
- Round pearl (R) : a perfect sphere or nearly perfect, with a maximum of 2 % distortion.
- Semi-round pearl (SR) : a sphere with a 2 to 5 % distortion is accepted.
- Drop (DR) or oval (OV) pearl
- Button pearl (BT)
- Semi-Baroque (SB)
- Baroque pearl (BQ) : is generally irregularly shaped
- Circled pearls with 3 rings or more on more than 1/3 of the surface.

The diameter
The price of a pearl varies with its diameter. The tahitian pearl has an average size of 8-12 mm and can grow to 18 mm.

The lustre
This is the reflective quality of the pearl’s surface, providing a reflection of light that is more or less perfect.

Surface quality
There are four levels of quality:

« A » quality: good lustre, perfect pearl or almost perfect with slight defects
on less than 10 % of the surface.
« B »quality: good lustre, pearl with a few imperfections which cover less than 30% of the pearl surface.
« C » quality: average lustre, pearl with defects on less than 60 % of the
surface.
« D »quality: numerous defects, lustre not being taken into consideration.

Colour 
The colour of a pearl varies according to the presence of different factors including the type of oyster, the natural environment and the choice of the mantle piece added during the grafting operation. Other contributing factors include the presence of minerals in the seawater, the degree of salinity, the quantity of plankton, the water temperature and luck!

Only Pinctada Margaritifera produces pearls with a wide range of natural colours. They generally have a body colour enriched by at least one overtone colour; and are classified in terms of rarity.

Keshi and Mabe
The Pinctada Margaritifera oysters that produces the Tahitian cultured pearl also produces keshi and mabe.

Keshi are small irregularly shaped; usually baroque shape, found during the harvest of grafted oysters which have rejected the nucleus. They are cultured pearls without nucleus.

Mabe : cultivated half pearl produced on the inside face of the shell of a pearl oyster. Also called blister pearl.