Vintage Crystal Identification

[Niall1]

Hello all

I am hoping someone may be able to help me, I have some of these vintage Rolex crystals and I am hoping someone may be able to help identify a part number or the reference that they are for.
I have scoured the Internet for similar examples and all are slightly off on size or design with the beveled top.

Dimensions are:
Diameter - 30.5mm
Inner Diameter - 28.9mm
Overall thickness - 5mm

Many thanks in advance for any help you may be able to provide