The upper tier gems are very desirable items to obtain for top tier players.
Is it worth it to combine gems in the lower tiers to build up to them (obviously upper tier gems must be combined or purchased)?
Is there a certain break point where it isn’t worthwhile to combine gems below that quality?
Worded differently, what price must the auction house demand for a gem before it is not worth combining them yourself?
As stated here, the new costs in the 1.0.3 patch deployed on June 19 are:
Quality Previous Cost New Cost Flawed 3 Chipped + 500 gold 2 Chipped + 10 gold Normal 3 Flawed + 750 gold 2 Flawed + 25 gold Flawless 3 Normal + 1250 gold 2 Normal + 40 gold Perfect 3 Flawless + 2000 gold + 1 Page 2 Flawless + 55 gold + 1 Page Radiant 3 Perfect + 3500 gold + 2 Pages 2 Perfect + 70 gold + 2 Pages Square 3 Radiant + 7500 gold + 1 Tome 2 Radiant + 85 gold + 1 Tome Flawless Sq. 3 Square + 20,000 gold + 2 Tomes 2 square + 100 gold + 2 Tomes
For example, to upgrade from chipped to flawless square:
1 Flawless Square = 2 square + 100 gold + 2 tomes = 2 * (2 Radiant + 85 gold + 1 tome) + 100 gold + 2 tomes = 4 * ( 2 Perfect + 70 gold + 2 pages ) + 270 gold + 4 tomes = 8 * ( 2 Flawless + 55 gold + 1 page ) + 550 gold + 8 pages + 4 tomes = 16 * ( 2 Normal + 40 gold ) + 990 gold + 16 pages + 4 tomes = 32 * ( 2 Flawed + 25 gold ) + 1630 gold + 16 pages + 4 tomes = 64 * ( 2 Chipped + 10 gold ) + 2430 gold + 16 pages + 4 tomes = 128 Chipped + 3070 gold + 16 pages + 4 tomes
Assume drop rates are going to remain unchanged and thus the prices of pages and tomes should be relatively stable (this assumption may be invalid, explain why if you disagree).
At what price for a flawless square does it become worth taking a DIY approach?
THIS ANSWER IS UPDATED AS OF PATCH 2.0/REAPER OF SOULS
All previous answers assumed an environment where the Auction House was a possibility for gem procurement. This is no longer the case in patch 2.0, and in order to get gems above the “Imperial” level, you must pay Covetous Shen to combine gems, as well as provide a few materials beyond simply money and gems at the highest levels.
So, is it worth it to combine gems?
YES (for Marquise and up).
In Patch 2.0, it is possible for Marquise gems to drop from level 61 and higher monsters. It is also possible for Imperial quality gems to drop from level 61 and higher monsters on Master difficulty and higher.
The gap between a Marquise gem and an Imperial gem is substantial, but gets even higher as you go further. Let’s take an example of an Emerald placed in your chestpiece…
- Marquise: +62 Dexterity
- Imperial: +100 Dexterity
- Flawless Imperial: +160 Dexterity
- Royal: +220 Dexterity
- Flawless Royal: +280 Dexterity
So, given that you can achieve a boost of +180 to a particular stat by combining gems over what you can get just from drops, it is absolutely worth it.
Below Marquise you will have to spend to upgrade Covetous Shen and then further spend to update the gems. If you can afford it, go ahead. More likely by the time you go through the effort you will either outgrow the piece of equipment or drop higher level gems. It’s really not worth the effort though.