VINTAGE JI 14K YGold .30ct solitaire diamond ring size 8.5

Vintage solitaire ring - it was my mother's first ring, with no carat marking, however she confirmed it is 14k yellow gold and features a .30ct diamond, with JI and Diamond marking inside the ring, and is approximately a size 8.5. She is uncertain and lacks information about its origins, though it was passed down from her mother, my grandmother. The ring is in excellent condition, having been meticulously maintained and preserved. 💎.