Jewel of Bless

Used to upgrade items up to +6. No chance of fail.
Can be stacked to piles of 10 and 30 for easier trade and some chaos combinations.

Jewel of Soul

Upgrades items from 0 to 9 but has 50% chance to fail. On fail from 0 to 7 downgrades the item with 1. On fail from 8 to 9 downgrades the item to 0. Items with "Luck" have 75% success chance instead of 50%. Can be stacked to piles of 10 and 30 for easier trade and some chaos combinations.

Jewel of Chaos

This is the most common jewel. It is used in all item combinations.

Jewel of Life

Upgrades the normal option of an item with 50% success rate.
On fail reduces the option with 1 level.

Jewel of Creation

Used for creating fruits that increase stats and resurrecting pets.
Also used for the socket system.

Jewel of Guardian

Jewels of Guardian are used for upgrading Castle Defenses and creating Life Stones. Also used to add a "pink" option to special items.

Jamstone

Used for creating Jewel of Harmony

Jewel of Harmony

Jewels of Harmony are used for adding a "yellow" additional option to your items.

Low Refining Stone

Used for increasing Harmony Options.

High Refining Stone

Used for creating fruits that increase stats and resurrecting pets.
Also used for the socket system.