Collagen contains specific amino acids â Glycine, Proline, Hydroxyproline and Arginine. These amino acids have a regular arrangement in each of the three chains of these collagen subunits. The sequence often follows the pattern Gly-Pro-X or Gly-X-Hyp, where X may be any of various other amino acid residues.ollagen contains specific amino acids â Glycine, Proline, Hydroxyproline and Arginine. These amino acids have a regular arrangement in each of the three chains of these collagen subunits. The sequence often follows the pattern Gly-Pro-X or Gly-X-Hyp, where X may be any of various other amino acid residues.
Opal is one of the world's most beautiful and precious gemstones, predominantly found in Australia. It is one of only six types of precious gemstones found on planet earth, sharing prestigious company with diamonds, rubies, sapphires, emeralds, and pearls.
Any kind of gemstone material can be produced as a doublet, especially expensive varieties such as sapphire, ruby and alexandrite. However, doublets are most often found in opal, since high quality precious opal is both very expensive and fragile. An opal doublet consists of a slice of precious opal usually glued to a black backing (common opal or glass), designed to imitate the appearance of a solid black opal.