Still figuring out some of the little things around here lol, I understand gold is used for having the woman in Esiors haven heal your party/purchases from the market and stuff, but what are scales used for? and how do I get the diamonds/blue gems?

Gold is used for general stuff (also, don't heal via the lady- pets will revive+heal over time so long as they aren't in battle (or in the Lost Grove, but that's not relevant to you right now, being the lv60+ area), or you can use potions (out of battle only) or elixirs (in or out of battle) to recover HP or draughts (also in or out of battle) to revive. You can buy these but it's better to just get them from mission reward satchels (guide to mission pets and missions to help get a good handle on how to get them)

Scales are used to buy things from the scale shop (the egglings aren't genrally worth getting, but here's scale shop science thread that goes over price>trait point)
they are also used to Nurture Boost egglings and hatchlings (which puts them to the front end of the nurturing grounds queue (that's what this icon indicates))

Diamonds are used to buy things from the diamond shop
, for buying some base styles for the avatar (that's things like noses, eyes, ears) and from the avatar item shop, for buying more stables, reclaiming pets you have released, can be used to buy more generator, party preset, and wardrobe design save slots. Might be more we're forgetting.

AP at this time are not used for much- they can be used to unlock certain avatar base styles, and more generator/party preset/wardrobe design save slots. The intention is that someday there will be an AP shop, but it is not currently top priority.

This was really in depth and helpful thank you so much!!