I did all of my harvesting in Nolantis Ruins, as all three gems spawn there, along the road on the edge of Medeus Altar. Diamonds are plentiful, but there are only three ruby nodes and seven sapphires.
Rubies:
* 474.8,2640.3,124.1 - guarded by a Reinforced Kalgolem
* 268.5,2633.2,116.2
* 345.1,2593.4,115.9
Sapphires:
* 503.1,2642.9,134.8
* 406.9,2726.8,117.6
* 418.2,2707.0,117.8 - inside corner of broken wall
* 413.0,2679.3,115.0
* 363.2,2662.2,112.7
* 434.7,2386.1,139.9
* 409.1,2404.7,131.2
Edited, Jun 13th 2010 10:22am by Bludwyng