Evaluating Pearls - Size

In the Cook Islands, Pinctada Margaritifera pearls tend to range on average between 10 and 13 millimetres with the very occasional pearl reaching 18 millimetres. With the exception of the button shape, the size of an Avaiki pearl is determined by the measurement along its shortest axis. It is measured in whole millimetres to represent one size category.

Within each size category, the millimetre range is from the lower whole unit up to but less than the next higher whole unit, e.g. 9mm will range from 9mm up to but less than 10mm.