Hallmark on this vintage mine cut diamond ring

by Callie
(La Verne, CA, USA)

What is the item? Vintage min cut diamond ring in platinum setting.


Can you please provide all background information?
33 diamonds total, 1 yellow center diamond, .5 ct and 32 smaller diamonds .05 ct each, 2.2 tcw

What are the markings? On inside of the band are the following markings: 900 plat, 100 irid, the letter
'G' inside of a diamond shape outline possibly a logo or signature of the designer or maker??