What is the highest quality of jewelry?

What would you consider to be the paramount quality of jewelry? Is it the rarity of the gemstones, the intricate craftsmanship, or the overall design that captures the essence of elegance and sophistication? How does one discern the highest quality from the myriad of options available in the market today? And furthermore, how does one ensure that they are investing in a piece that will not only withstand the test of time but also retain its value and beauty for generations to come?