Resin is a durable and transparent plastic that is especially suited for jewelry-making because of its ease of use. It begins in a liquid form, but after being casted, becomes quite durable. Special resin molds with smooth surfaces are created to give it a glossy finish.
Opal is a hydrated amorphous form of silica. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt. Precious opal ranges from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black. Of these hues, the black opals are the rarest, whereas white and greens are the most common.