Celtic tribes, led by Druids are known to have used crystals for divination in Britain as early as 1,500 B.C.,
The Greek traveller, Pausanias described catoptromancy in his writings.
Before the Temple of Ceres at Patras there was a fountain, separated from the temple by a wall, and there was an oracle, very truthful, not for all events, but for the sick only. The sick person let down a mirror, suspended by a thread till its based touched the surface of the water, having first prayed to the goddess and offered incense. Then looking in the mirror, he saw the presage of death or recovery, according as the face appeared fresh and healthy, or of a ghastly aspect.
In the Shahnameh, an epic written in the late 10th century, there is a description of Jaam-e Jam, a cup apparently containing the elixir of life, being used by practitioners to see the layers of the universe.
Dr John Dee (1527–1608) mathematician, astronomer, astrologer, geographer, and consultant to Queen Elizabeth I, and his assistant used a crystal ball. The ball is now housed in the British Museum in London.
The Tools of Scrying
The tools used by the practitioner have been many and varied, depending in the culture and the availability of materials, but nearly all have involved items with a reflective surface.
There is no right or wrong item for scrying. It is a matter of personal choice and what you feel comfortable with using.
Air, normally using atmospheric conditions or clouds, is known as aeromancy. Who hasn't, as a child, made pictures with the clouds?
Crystal Ball, both natural stone or in more modern times, glass.
Earth is known as geomancy.
Fire, both using flames and smoke, is known as pryomancy. Another one that I can relate to, making pictures with the flames can be quite mesmerising.
Mirrors known as catoptromancy, or mirror gazing
Water, or any other liquid, is called hydromancy.