Jeweler is a dexterity based skill allows the character to make spell scrolls. A gem cutter is required to use this skill.
Out of all the crafting skills, jeweler is probably the most useful because of how fast you have access to inferior material scrolls and change material scrolls. The materials needed to make these scrolls is also very easy to get and a couple runs in the puppy cave will give you enough materials to make dozens of these scrolls. Of special note is the change material scroll. When blessed, change material scrolls will act almost like superior material scrolls. By making several change material scrolls and blessing them all at once, it is possible to upgrade all of your armors to high level types, making it possible for a low level character to run around with massive amounts of DV/PV. Because of this, be on the lookout for +jeweler equipment (in Elona+, wearing a Peridot on your neck will increase the skill by 6). Inferior material scrolls are adequate until you make Change Material.