Wood can be simulated by mixing browns, white, black and even reds and yellows to look like the real things. This Faux Wood Pendant by Creative Sisters has the look of real inlaid wood.
Hand Carved Faux Stone Petroglyph Earrings by Cynthia Blanton look like an ancient artifact carved from sandstone.
Turquoise can be created using polymer clay, Such as this Faux Turqoise and Copper Necklace by Amazing Designs.
Shell can be reproduced in polymer clay. These Faux Aubergine Shell Earrings by Gaia Copia Look like they just came from the sea.