What’s the difference in luster between the South Sea pearls and the Akoya?

Thanks!

Mary G.

Des Moines, IA
 
Dear Mary, The main differences between South Sea pearl luster and Akoya luster are the sharpness of reflections seen in their surfaces, and brightness. Akoya pearls are known for their bright, glossy luster and razor-sharp surface reflections- when you look to evaluate an Akoya pearls’ luster, reflected light on the surface should have sharp, crisp borders and you should be able to distinguish some of your facial features staring back at you (with really great Akoya pearls you’ll be able to make out your entire face!). South Sea pearls have a much softer, more satiny glow to them; light reflected on the surface of the pearl will be slightly blurry on the borders and it’ll be rather difficult to make out facial details. There are a few reasons for this: nacre thickness, luster treatments and the water temperature of the pearl farm during cultivation.
 
The luxurious South Sea pearls have what is considered very thick nacre around the bead nucleus- typically measuring between 2.0-6.0mm! The attribute known as luster- which can be characterized as both that subtle inner glow that entrances the eye, as well as how well the pearls’ surface reflects light and objects at the viewer- requires a light source striking the surface of the pearl and then traveling through to the center nucleus, refracting and reflecting light throughout the various layers of crystalline material (nacre) and then bouncing back towards the surface. Two to six millimeters of opaque crystal all of a sudden seems like a huge distance for light to travel through! The thick nacre deposited around the nucleus of the pearl is the result of a cultivation period that spans at a minimum 2 years, and the warm, clean waters of the South Seas which speeds up the oyster’s metabolic processes, encouraging rapid nacre deposition around the bead, and a looser aragonite platelet arrangement that results in a softer glow.
 
By contrast, Akoya pearls are cultivated in the much colder waters of Japan and China for a drastically shorter period of 9-16 months! This means that the nacre deposits around the nucleus are much thinner than that of their South Sea cousins, with an average of .3-.6mm showing around the bead.  Additionally, the colder waters actually slow the oyster’s metabolic rates, leading to slower nacre deposition, and tighter, contracted nacre layers which will transmit light beams much more rapidly and give the impression of sharper, glossier luster that the Akoya pearl is famous for the world over.
 
After harvest, the Akoya pearl is typically sent to a processing center in China, where various treatments are applied to help the pearls maintain their uniformity of look (another famous attribute of Akoya pearls is that they are all almost perfectly matched). One of these treatments can often be a luster treatment, in which a thin veneer of glossy lacquer-like substance is lightly applied to the surface of the pearl in order to enhance its’ shine. Luster treatments do not harm the durability of the pearl, and are considered standard industry-wide. It should be noted that South Sea pearls (both the Silver and Golden varieties), are not treated or processed in any way other than a bath after harvest to rid them of any left over smell, and gentle tumbling with wax-covered walnut chips, soft bark and cork pieces for about 20-30 minutes to naturally enhance their outer shine.