Size of the nucleus

[lochi]

I don't know whether this is the right forum to post this Q in (since it could go under tahiitian pearls/ss/ or fw) but here it is: how big is the nucleus used in akoya/tahitian/south sea pearls? does it depend on the size of the pearl? or the type of pearl? or the location or farm it is cultured in? and if it is a standard size mop bead that is used, then that would mean (logically) that the bigger the pearl the thicker the nacre, right?

I don't know whether there has been a discussion of this topic before -- i've read most of the other threads related to fw/ss pearls but couldn't find info on this... if it has been discussed elsewhere, pls. point me to it

I'm very new to the whole pearl scene and started collecting a couple of years ago. To be quite honest for many years I did not even like pearls eek: ) because I always wondered: what so great about a round ball that doesn't sparkle (like diamonds). that is, until i rec'd my very first fw strand for my b-day... and now I can't imagine owning any other type of gem. I love this forum and am so happy that I found it... great info and great people. would love any any help on this subject.

 

[Zeide Erskine]

Hi Lochi,

You probably have found out already that freshwater cultured pearls are for the most part solid nacre and the ones with a bead inside cost more anyway.

Akoya PPBs (pearl plated beads) have a large bead and little nacre covering. On principle, the smaller the akoya the greater its ratio of nacre to nucleus and vice versa. In short, if you like akoyas buy small ones. Big akoyas are a waste of money. They are also heavily treated and the treatments wear off. The bead largely determines the final size of the PPB. The current standard for thick nacre in akoyas is 0.25mm (that is the thickness of line drawn with a freshly sharpened number 2 pencil) but most commercially available akoya PPBs come nowhere near that.

White and golden South Sea cultured PPBs have more nacre relative to the bead than akoyas or Tahitians but not always. The so-called baby South Sea pearls are in most cases overpriced freshwater pearls and when not under-nacred South Sea indicator PPBs. Big ones can have enough nacre to make the doublet standard of 30% real gem and 70% filler. Most are more in the 10%/90% range.

Tahitians have gone the way of the akoya with a statutory minimum of 0.8mm (think thin spaghetti uncooked) nacre thickness. The average is not much more and it has been found that some Japanese pearl processing factories peel nacre off Tahitians to make them rounder and then treat them with everything from colored oils to metal vapor deposition to coatings of Mary's glass to give them the AAA look. Those are aptly nicknamed Fabulitians. In principle you get the best deal in terms of gem/filler from small Tahitians because the 0.8mm minimum applies to 8mm PPBs as well as to 18mm PPBs.

Zeide

 

[lochi]

Hi Zeide,

Thanks for info! I was under a clear misconception thinking that the larger the PPB the greater the bead-to-nacre ratio -- but clearly thats not true! do akoya pearls loose their lustre over time due to the thin layer of nacre? I was going through the other threads/forum and came across the ebay listing discussion regarding a strand of akoyas which many other members here said had worn down to the bead. is this the eventual fate of all PPBs? or does this happen primarily due to neglect or mistreatment of the pearls? and what about fw pearls? do they loose their lustre over time as well? Thanks.

lochi

 

[Zeide Erskine]

Hi Lochi,

It is the fate of all PPBs to eventually wear down to the bead. In short cultured akoyas that can be months and in thick-nacred South Sea PPBs that can be two generations (at about 25-30 years per generation). When the luster is enhanced, the enhancement will eventually wear off. The less treated a high quality pearl is, the longer it will last. There are some still quite lustrous natural freshwater pearls that are well over a thousand years old. Larger pearls wear down somewhat faster than small pearls but in natural or untreated solid-nacre cultured pearls the wear is going to be near undetectable unless you monitor them over eons. The reason for that is that the conchiolin in its original form will keep the pearls inherently elastic and thus wear-resistant. Treated pearls are for the most part bleached, which denaturizes and shortens the conchiolin thus making the aragonite platelets more prone to flaking and abrasion.

Zeide

 

[lochi]

Hi Zeide,

I'm a little saddened to learn that my akoya pearl earrings won't last long enough to be passed down to my kids ... ah well at least I will enjoy them in my lifetime. I have just finished reading the thread entitled "use of the term 'pearl plated beads'" and found it very informative! its hard to find such a heated (not to mention well represented and open) debate online in the jewelry industry. Thanks again for the info Zeide. I googled the word "conchiolin" and learned a lot about nacre production and structure of the protein . From reading all of the threads/posts/forums here, I gather than most of the fw pearls commercially available would be treated in some way -- bleached, coated, waxed, etc. On some level as a consumer I accept this because I can imagine that otherwise the pearls would not be appealing. ON another level as a collector (albeit novice one) I'm saving my money to get a natural pearl one day. thanks again for all the info!

lochi.

 

[Ragnorak]

how big is the nucleus used in akoya/tahitian/south sea pearls?

I'm not sure about akoyas but for the other two the bead size usually ranges from about 2.0bu to about 2.6bu for a young oyster about to produce it's first pearl.

You can find a convertor which will change bu to centimetres or inches here. A bu is roughly 3.03 millimetres.