The basic colors and their attributes are listed above, but here it is again: Red: Strength, Blue: Willpower, Yellow: Endurance, Green: Aim/Cunning. Apparently the results of combining shards are the same regardless of your class, but it does seem that using the same color multiple times yields a higher level Relic with better stats.
Below are some of the known combinations:
RYR – 8 Strength, 30 Endurance, 11 Willpower, 14 Accuracy
RRB - 25 Endurance, 10 Willpower, 10 Presence, 19 Force Power
YYY – 18 Aim, 60 Endurance, 34 Cunning, 30 Absorption
RYB – 6 Strength, 12 Endurance, 6 Willpower
GBB – 9 Aim, 17 Endurance, 9 Cunning, 9 Accuracy
YBB – 7 Strength, 20 Endurance, 5 Willpower, 10 Defense
RBB – 17 Endurance, 7 Willpower, 7 Presence, 13 Critical
RBG – 6 Aim, 6 Endurance, 12 Cunning
GYY – 17 Endurance, 9 Cunning, 9 Presence, 9 Crit
RYY – 7 Strength, 17 Endurance, 7 Willpower, 13 Accuracy
