Vintage 18K 750 Gold Ruby or Sapphire Booch

Vintage 18K 750 Gold Brooch with 7 Genuine Rubies or Pink Sapphires. Tested as precious gemstone with my Diamond tester I just don’t know which for sure. Weighs 4.45 grams. Approx 1 1/2” long. I have tested this at least 5 times to be sure, and it’s solid 18K yellow gold! The stem passes for gold also! The stamp is hard to make out there’s a makers mark and then maybe a 5 sided box with something also. I’m not sure. Really pretty white enameling. Dainty Flower brooch. EUC. Thanks for looking!