The Problem: As you reach around 440 Jewelcrafting, the JC window becomes a huge list of greyed out, unordered designs. You can no longer quickly see which gem is of what quality when everything has greyed out for you.
My Solution: Color gem designs by their quality, and emphasize WotLK gems by fading out 'old' designs. The result is GemJar.
This addon colors the designs in the JC tradeskill window (your own or linked ones) by the quality of the created gem or item. It fades out pre-WotlK designs, but will still color those by their respective quality colors. So, for example, TBC epic gems will be a faded out purple, while LK uncommon gems will be bright green. Bind-on-pickup gems such as the Dragon's Eyes get a distinct color (the Heirloom color).
Works with AdvancedTradeSkillWindow, except the Custom Sorting list.