Gems are precious stones which sometimes appear on the ground when digging (emeralds/star emeralds only) or mining (all gem types) in caves, in which their quality is capped by your mining skill and/or tile quality. They can also be received as a gift from the gods when praying as a priest of over 50 faith.
- Gems can be either sold to another player for varying amounts of money or can be used by priests to "vessel" their favor, saving it for later use.
- Gems never decay, although 'using' a vesselled gem to recover favor causes it to lose quality each time. The amount of QL lost is equal to the amount of favor taken to fill the priests favor bar divided by 2. E.g. a priest has 20 favor and 60 faith, the gem will provide 40 favor at a cost of 20 QL. Casting vessel on a gem under 10QL will lower the QL of the gem by 3, and store no favor - useful for grinding the channeling skill.
- All the "common" gems are equally rare and at equal qualities worth the same and store the same amount of favor.
- The Black/Star gems are rare versions of their respective "common" counterparts. All the "rare" gems are equally rare, and at equal qualities, they are worth the same and store the same amount of favor. Their value and ability to hold favor is double that of the common ones.
- Some unique gems were received from easter eggs in 2006. Another unique gem which is not found anymore is the Glass Crazy Diamond.
- Gems cannot be stored in any kind of bulk container. Consequently, many players opt to store them in chests, satchels, backpacks, etc.