How are natural freshwater told apart from cultured?

[Valeria101]

Anything to look for at first sight (aside their settings and pedigree)?

How about lab methods?

Since pictures never hurt a thread , here's some little examples of what I am talking about, FleaBay direct Two Scottish pearls in old rings: one smaller one larger.

 

[The Pearl Outlet]

A lab will generally x-ray the pearl to determine if it is natural. Even FW tissue nucleated pearls are distinguishable from natural pearls this way.

Based on the date of the rings, if the pearls are real, they would most likely be natural. Especially the rounder one, since cultured rounds weren't produced until the early 1900's.

 

[Valeria101]

Thanks!

A lab will generally x-ray the pearl to determine if it is natural. Even FW tissue nucleated pearls are distinguishable from natural pearls this way.

Any idea what are they looking for in the Xray's ?

 

[preswine]

Any idea what are they looking for in the Xray's ?

Theoretically they could be indistinguishable, but in practice there will be evidence of tissue nucleation inside the pearl. The structure of the layers of nacre will reflect the shape of the piece of tissue used to nucleate the pearl. Also, although the tissue disintegrates before the pearl is finished forming, it will most likely be fossilized in conchiolin at the center of the pearl. Since no piece of tissue is perfectly small and perfectly uniform, this kind of evidence will be imprinted in the pearl and will be visible in the xray.

At least this is what I recall from interrogating various gemologists about how they interpreted the xray of my natural pearl. If you really want to know for sure then get a copy of the Elizabeth Strack's book.