Contra luz opals are very much like crystal opals but have the ability to also create color flash as light passes through from the opposite side. This unusual characteristic makes these opals more interesting and therefore may demand a higher price. Contra luz opals may also have the flash normally resulting from reflected light in addition to its characteristic flash. Crystal with matrix is composed of crystal opal material naturally backed by or surrounded by the natural matrix or Rhyolite material after it is cut, shaped, and polished. The value of these opals vary in price depending on the rarity and esthetics of the piece.
Most Mexican varieties are inexpensive.
Fire opal is an orange or reddish opal from Mexico that has no play of color or iridescence and is usually faceted. It implies that there may be fire or iridescence in the stone when there isn't. Its name was derived from its base color which is the color of fire or a flame. These stones demand a high price when faceted from highly transparent reddish orange color material. Doublet opals are composed of two layers.