both Natural pearls and natural teeth are made from CALCIUM compounds. Natural Pearls are composed of nacre which is a combination of aragonite or calcite with the inclusion of an organic binder, called conchiolin.
Tooth Enamel's primary mineral is hydroxyapatite, which is a crystalline CALCIUM phosphate. The large amount of mineral in enamel accounts not only for its relative strength but also for its brittleness. Tooth enamel ranks 5 on Mohs hardness scale, around the same as Pearls.
The only way to positively identify a natural Pearl is by X-raying the pearls. Natural Pearls are composed of layer upon layer of calcite. Using x-ray as diagnostic tool can establish whether your Antique pearls are Natural pearls.
This is where it pays to have a good relationship with your dentist. I do not advise you to have an on-line appraisal if your Pearls do turn out to be Natural Pearls.
Where do you go from here? Contact me for appraisal or consultation.
Best Wishes,
Yvonne Hammouda-Eyre
M. Staines, W. H. Robinson and J. A. A. Hood (1981). "Spherical indentation of tooth enamel". Journal of Materials Science