This is a Harvesting quest. Essencetapping (399p) or better is required to complete this quest. If you do not have the skill to harvest the items needed yourself, most (but not all) Harvesting quests will update no matter how the items are obtained. You may buy or trade for them, or receive them from a friend.
You can see where the Resource Nodes are located in the following categories:
† All quests reward XP but NCSoft is fond of changing the amounts frequently, to the point that it is simply not wise to try to track the exact amount in a wiki.
Quest Notes
The chance to harvest each of the rares is approximately 1%. Rubies, Sapphires and Diamonds are found in Heiron and Theobomos. These are rare harvests (less than 1%) so expect to spend hours, days, and even weeks doing this. Be sure that you are wearing the Expert Essencetapping Ring or you will never find any. Beyond that there is no trick, just keep harvesting.