Citrine is a variety of quartz whose color ranges from a pale yellow to brown due to ferric impurities. Natural citrines are rare, and most commercial citrines are heat-treated amethysts or smoky quartzes.
Lapis is a deep blue semi-precious stone prized since antiquity for its intense color. The intense blue color is due to the presence of the trisulfur (S3) radical anion in the crystal. Lapis lazuli is a rock whose most important mineral component is lazurite. Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, small statues, and vases.