Please could you let me know what this is and of what time period?

by Marga Dobma
(The Netherlands, Helmond)

From an inheritance I got, the above item, which I think is a pendant. There are no hallmarks on it. It is of rose gold (colour) and also there is a silver (?) pattern on it.

I have tested the stones and came to the conclusion these are table cut rose diamonds.

Please could you tell me what orgigin it has, and is it of gold?
Thanks for your time and answer,

Marga Dobma