To get the Sapphire, first use Cut on the door in Ruin Valley, then go down the hole in Dotted Hole. Next, there is a puzzle. Start by going down the front hole, then the left hole, then the right,...
Sapphire is the blue form of the mineral corundum. Which is the same as Ruby. However, Sapphire comes in many more colors than blue. It comes in pink, yellow, white, green and orange.