Gemstone Grotto is a cave in Rookridge, accessible via a short stretch of beach near the Hobbe Cave. The area is a medium-sized winding cave filled with pools of water and crystalline formations on the ceiling and floor; hence its name. It contains several beetles, a silver key, and an Ancient Scroll used in the Archaeologist quest. Following the cave to the end leads to a treasure chest containing 200 gold. Where you can find the silver key, there is also a statue of a Shadow-Worshipper.