The addition of sockets and the idea of specific arrays of jewels adding non-linear benefits opens the door to much larger demand for selling weapons. For those who have forgotten the details of the jewelcrafting preview in the last 6 weeks since it's been published, each socket will have a color associated with it. If you match a gem to the socket and do that for all the sockets, you receive an added bonus as a characteristic of the item itself.
No one buys the former anymore and the latter is too costly to turn a profit and not very desirable anyway
I don't know melee classes well enough to make a clear example, so let's just pretend that some profession will be able to make caster staves.
You make several different schematics for weapons that reward different colored jewels. You could have the "General Purpose Staff" which encourages different colors of gems and rewards that. You could have a "Mana Regen Staff" that rewards adding mana regen jewels, a "Mana Battery Staff" that rewards +Int jewels, and a "DPS Staff" which rewards + spell damage jewels. If this is in fact the case, there could be obscene demand for weapons since there will no longer be the all around perfect weapon. Instead, you'll have weapons that you can customize for specific situations or personal tastes. This will encourage everyone to get even more stuff since there are situations where a specialized staff will be preferably to a specific staff. Unless of course you have Atiesh, in which case, good game.
I'm assuming, of course, that there's some shared attributes to colors of jewels. We can't tell definitively yet because we don't have enough data, but it's not an unreasonable jump given our tiny sample here: http://www.worldofwa...elcrafting.html
Red: + Spell effects (healing or damage)
Yellow: + Intellect
Orange gems, which count as Red and Yellow, get both +plus spell effects and +Intellect
The Purple gem doesn't fit neatly into my explanation. It counts as both Blue and Red and gets + spell effects but instead of + Stamina, it gets + mana regen.