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.
Accessing the cave[]
To get to the grotto, fast-travel to the Hobbe Cave in Rookridge. (If fast-travel is not available, the grotto is located on the extreme northwestern portion of the Rookridge map). Immediately turn around and exit the cave. You will be on the beach shore of Rookridge. From the beach, after killing the hobbes, swim to the beach to the right, kill the hollow men on the beach, and follow the sand to the cave entrance.