Deep inside the Gem
The precious opal was discovered in the middle Ages and its name comes from the ancient Indian word "Upala" which means ‘precious stone’. Unlike other gems, opals do not form crystals. Their amorphous silica structure diffracts light and deep inside themselves they reveal the color of all gems. The complete story in DiveInside: https://taucher.net/diveinside-diving_the_slovak_opal_mines-kaz7137