Prismatic gems are unique to Chapter 0.
Prismatic gems are created by combining at least one of each gem color into a single gem, in order to activate all of the specials at once. They receive no fire rate bonus, but they do receive a damage bonus. They are (generally) best used in traps, though they have some useability in towers.Strategy thread
While all of the colors are represented in a prismatic, they will each be capped at a lower value than they would be in a triple gem, and will not be capped equally. if the components were all printed out, the strongest would be on the left, and the weakest on the right. For example, with a gem composed of yellow-lime-red-cyan-purple-blue-green-orange, yellow would be the strongest, and orange would be the weakest.
Green has no maximum at all, blue only has a maximum in terms of slowing percentage, and this is not affected by being in a prismatic. Additionally, it may be hard to tell what the order is if the specials are below the maximums.
Working with prismatics
Prismatics are the most powerful type of gem available in chapter 0, mostly because they do everything at once: stop the monsters, drain the monster armor, kill the monster, all while adding to the mana pool. However, their true value is the fact they may be supergemmed like a mixed gem (no pausing to transmute needed), and still receive a damage bonus like dual or pure gems. The fact that they can do more damage/mana spent than any other gem is a very nice bonus.
There is a catch: they need to be at least grade 11, or they will be a waste of time and mana.
When a prismatic is built, chances are that the specials will be in the wrong order, especially if making grade 14+ prismatics. To change the order of the specials, drag gems ONTO the prismatic in the inventory. example: to simply maximize yellow, drag a yellow gem onto the prismatic. To make the first three components yellow-lime-red, grab those three gems and drop them onto the prismatic in reverse order, or grab a yellow gem, drop it onto a lime gem, take the yellow-lime and drop it onto a red gem, then drop the whole thing onto the prismatic.
lastly, to change the hue without changing the special order, drop/combine the prismatic onto gems close to the desired hue.
Warning
As powerful and useful as prismatics are, it is a bad idea to fill every trap space on a long level (especially #78) with prismatics, as they cause the most lag of any gem type. They also underperform R/O and R/O/X gems for the purposes of mana farming. [1]