@chirsgsaid I was obligated to turn this comment in the ocean feedback thread into it's own thing, so here it is.
We all know Crab King and his loot sucks, and despite how plentiful gems are, they don't really have that many uses outside of purple and green gems. The goal of this rework is to not only provide unique and interesting uses for the gems, but to also make Crab King a boss you should want to fight and be excited about getting his loot.
The default trident should have it's ocean based damage removed and instead be given a flat amount of damage, 51 makes sense since this requires crab king in order to be defeated, but an option I'm much more fond of is having 35-40 damage, increasing to say 59.5 when you have a gem socketed in it. Speaking of gems, each one would have their own effects. Each gem should have at least 150 uses of durability. Gems can be removed at will, but will shatter if missing even a single point of durability, or they can be directly swapped out with another gem, having the same shatter effect.
Red gem - Something fire related seems obvious, however red gems also have the power of revival, so healing isn't off the table either. Due to the impracticality of fire during combat I'm going to lean towards healing, and since the bat bat already has the niche of healing on hit, I'm thinking healing on enemy kill would be interesting.
Revision: chirsg suggested that red gems could heal creatures with a right click ability. I'd have to disagree, simply for the fact that it'd feel out of place having the red gem be the only one with a right click ability, and while I could think up abilities for each gem, I honestly think it's fine leaving the trident with just the geyser ability.
Blue gem - Freezing enemies is obvious, but instead of rendering them immobile I think slowing their movement speed and/or attack speed is more unique, allowing you to effectively increase your dps as you're able to get more hits in.
Purple gem - Could summon a terrorclaw claw, but that feels a little too similar to the thulecite club, so instead maybe it could poison the creature it's being used against with nightmare fuel, dealing ramping damage over time, making it great for bosses with large health pools.
Green gem - Could cause enemies to drop rarer items more frequently, but there's a shockingly low amount of rare drops in this game, the krampus sack being more or less the only notable one, so causing enemies to drop extra items seems more useful.
Yellow gem - Produces a small area of light (similar to a very hot thermal stone) around the player, which grows and eventually remains even if the player isn't holding the trident while attacking enemies, eventually rivaling the lantern in terms of light. A bit redundant perhaps, since having yellow gems usually means you could instead make star caller staves and use those for light, however those are stationary while the trident is portable, plus they cost 2 gems instead of one.
Orange gem - Provides the player with a shield that blocks all damage from one attack every few seconds, as long as you avoid getting hit. Would instead have 15 uses per orange gem, however an argument for 10 uses could be made considering how little use orange gems have, especially due to the refuelability of the lazy forager.
Iridescent gem - Instead provides 72.25 damage (equivalent to the morning star vs a wet target). Removes the sanity auras of enemies (note: would not reverse auras like bee queen crown). At first I thought 300 uses would be appropriate due to the little amount of time available to convert star caller staves into moon caller staves, however the moonstorm throws a wrench in that idea completely. I personally would prefer if the moonstone event would be disabled while moonstorms are occuring, allowing the 300 durability to work fine, as balancing this rare gem around a fairly late game event where you can consistently get 2 gems a night would take away from the feeling of this gem being extra special and powerful.
Revision: The void robe now provides immunity to insanity auras making this more or less redundant. Sure it's not inherently bad having 2 items that do the same thing, but considering the original intention was to make the Iridescent gem feel extra special. The first idea I had was to let the player gain 1 sanity every few hits, but that's not particularly interesting. A much more interesting ability would be to revive creatures killed within a few seconds of being hit by a Iridescent gemmed trident and have them fight for you for a short duration.