[olmander]

Hi everybody,

In search for an enchancer for my newly produced long grey necklace I came across a brooche with a very big (30 mm) blister pearl.

I wonder if these pearls are salt-water or FW ones. Does anybody know from what sort of mollusk or oyster it may come?

And a more practical question: I don't think I keep it as a brooche, it has such a nice luster and colour that it is worse making a ring with this pearl. Any ideas about designs for large blister pearl rings?

Olga

Her are the photos (it is not that blue as on the picture, rather lavender-greyish):

[Slraep]

This is dyed opercula.

Slraep

[olmander]

Sorry, I am not an expert - what is opercula? Is it the name of a mollusc?

[Slraep]

Oops, details, details, sorry it's operculum(plural: operculi) or osmena. A piece of specially secreted shell that is domed and blocks the entranceway to a gastropod's soft body tissue when that tissue is retracted. Pretty much like a trap door---keeps moisture in while keeping predators out. It must also have some other brilliant technological use for a gastropod that we humans are yet stupid about.

Slraep

[jshepherd]

It is also called turban snail shell or cat's eye.

[olmander]

I pretend I understand..
But from what sort of shell it is? Oyster? Looks too big for a FW one but maybe I am wrong.

Although this is from a rgular Chinese shop, I would guess that this is a river one or not?

[Slraep]

Originally Posted by olmander

I pretend I understand..
But from what sort of shell it is? Oyster? Looks too big for a FW one but maybe I am wrong.

Although this is from a rgular Chinese shop, I would guess that this is a river one or not?

Hi olmander,

Alright! Pretend this---it's from a big gastropod. Usually saltwater.

Slraep

[Caitlin]

Hi Olmander

Osmena aka osmina comes from a nautilus shell. Your osmena is blue as are many of them. I don't know why they don't come in any colors but white and blue. I think slraep is correct when she says it dyed.

[olmander]

Oh good! I googled haliotis out, it is all clear now. Thank you for help!

[Slraep]

It has not really been discussed on the pearl forum, but the operculum has a fascinating makeup....

"The operculum is not a product of the mantle. It is produced by a separate organ, the opercular disc, a pad of specialized secretory epithelial cells located right where the operculum is attached - on the posterior, dorsal aspect of the foot. The opercs of some species are secreted spirally, with new material being deposited on one edge only, and the operc gradually rotating on the opercular disc as it grows. Others are secreted concentrically, with new conchiolin being deposited on all edges of the operculum simultaneously, without rotation of the operc."

Slraep

[olmander]

This is indeed something comletely new to me - very interesting! I am digging on Google - looks really fascinating!

[olmander]

It stands that haliotis has something to do with abalone shells, or is at least from the abalone family - do I see it right?

[Slraep]

Cat's eye comes from the Turbo species: Indo-Pacific Turbo petholatus

Other operculum can come from:

South African Turbo sarmaticus
Green Turban Turbo marmoratus
Turbo argyrostoma(small)
Turbo rugosum

Slraep

[olmander]

Thanks! I am going to dig further for these new ones...

Olga

[Slraep]

Originally Posted by olmander

It stands that haliotis has something to do with abalone shells, or is at least from the abalone family - do I see it right?

Abalone is a type of snail or Haliotis. But the ones with operculi are the ones that are turban shaped(twisty).

Slraep