I know that was an easy one!
I have Badges with such stones in the Lambda that range from Pearls, Saphires, Garnets, Rubys, Diamonds, and Opals with combonations of stones.
Have both Yellow (Most Common) and White goldl.
One with curved convexed Lambda (Older).
C & C will show some each issue, but not nearly as many when were shown on web site.
You can order variations of stones for the Lambda, but Pearls only in the cresent. White gold is more expensive.
4 of my favorites:
1. White Gold with Saphires in Lambda. Mu original Badge.
2. White Gold, with 3 saphires, 8 diamonds.
3. Yellow gold, with emeralds and amythists, P G & G.
4. Yellow gold, with 3 rubys and 8 opals.