What did I do this time?

[massrog]

Hi all I just got myself into a little hot water buying this strand for the clasp as I thought it might be nice on one of her better strands. They were billed as "natural-antique". Several look worn at the thread holes so I believe they are old but can you please chime in on what they look to be? By the way they are approximately 8mm.
Thanks as always!
Roger

 

[jshepherd]

It looks like you've got a strand of older akoyas that look to be a mix of shapes, near-round to baroque.

 

[pearlescence]

If they were re-strung with a just off-white thread they would look whiter. That thread is wearing thin and looks yuck. Suspect they need a good wash too, as they are visibly more yellow than the two pearls on the (very nice) clasp.

 

[massrog]

If they were re-strung with a just off-white thread they would look whiter. That thread is wearing thin and looks yuck. Suspect they need a good wash too, as they are visibly more yellow than the two pearls on the (very nice) clasp.

I spoke to the auctioneer, and he did say that they need cleaning and a re-string. Does anyone have a guess as to age particularly of the clasp?

 

[2thdktr]

I spoke to the auctioneer, and he did say that they need cleaning and a re-string. Does anyone have a guess as to age particularly of the clasp?View attachment 467309View attachment 467310View attachment 467311

To me, it looks like an 1980"s remake in a Deco style.

 

[CortezPearls]

I thought it was an 1970's piece, made in Mexico.

 

[massrog]

They finally got here. Boy did they need that bath! There are a few worn ones but all in all very presentable I think.
Before:

After

 

[massrog]

Upon further examination I noticed an area on one pearl where the Nacre was worn through. I looked at it with a 30x loupe and found another layer worn through as well. I remember reading a comment from Jeremy about "peeling pearls in times gone by. How many layers of Nacre build up on cultured pearls generally? Below is a shot of the wear patterns. There is a circle shining inside the blue.

 

[jshepherd]

If you were to take a cross section of the nacre and examine it under a microscope, you'll see the nacre isn't deposited in a single encompassing layer, but rather in a brick-like structure. The aragonite crystals are the bricks and the conchiolin is the mortar.

Aragonite crystals vary in size based on the type of shell and growth conditions, but the average thickness ranges from 0.3 to 0.8 μm (μm = micron/micrometer = 1/1000th of a millimeter). Akoya, especially fine akoya, will have the thinnest crystals. The length the crystals is about 10x the thickness, so around 3-8 μm depending on the same factors.

If an akoya pearl has .4 mm of nacre and thin aragonite crystals of 0.3 μm, then the number of layers can be calculated by 0.4 mm/0.3 μm (0.3/1000 mm) = 1,333 layers.

 

[massrog]

We had a few strands we purchased as a lot a while back and I thought one might blend with the one posted here to make a graduated long strand. What do you think?

 

[CortezPearls]

The look so much better after their bath!

 

[pattye]

Yes, combine strands! There are already variations of color and imo, it appears they will look fine mixed. I prefer some color variation.You will be able to set aside any damaged pearls and still have a long lovely strand.

 

[massrog]

Yes, combine strands! There are already variations of color and imo, it appears they will look fine mixed. I prefer some color variation.You will be able to set aside any damaged pearls and still have a long lovely strand.

Thanks pattye! Those were my thoughts exactly!

 

[massrog]

If you were to take a cross section of the nacre and examine it under a microscope, you'll see the nacre isn't deposited in a single encompassing layer, but rather in a brick-like structure. The aragonite crystals are the bricks and the conchiolin is the mortar.

Aragonite crystals vary in size based on the type of shell and growth conditions, but the average thickness ranges from 0.3 to 0.8 μm (μm = micron/micrometer = 1/1000th of a millimeter). Akoya, especially fine akoya, will have the thinnest crystals. The length the crystals is about 10x the thickness, so around 3-8 μm depending on the same factors.

If an akoya pearl has .4 mm of nacre and thin aragonite crystals of 0.3 μm, then the number of layers can be calculated by 0.4 mm/0.3 μm (0.3/1000 mm) = 1,333 layers.

Thank you Jeremy! That was exactly the tutorial I needed. Do the farms start with varied sizes for the beads to generate varied sizes in the same timeframe or do they allow longer growth periods for the larger pearls?

 

[CortezPearls]

Thank you Jeremy! That was exactly the tutorial I needed. Do the farms start with varied sizes for the beads to generate varied sizes in the same timeframe or do they allow longer growth periods for the larger pearls?

Yes, all farms will use diferente sized beads/nuclei. Each technician will select an appropriately sized bead, depending on the oyster's condition (my grampa used to say, "the size of the rock you choose depends on the size of the toad you want to hit!").
The time period remains the same, but there may be farms where they allow some more time.