The Crown Jewels are a collection of priceless jewels and artifacts that have been collected by the British monarchy over centuries. They include two of the most precious gems, rubies and opals. Rubies are a deep red gemstone that is known for its hardness and beauty. Opals are a unique gemstone that can display a variety of colors in its iridescent surface. Both of these gems are part of the Crown Jewels and are highly valued.