Materia showing up red and/or +0?

[Rydia_Lynn]

Curious what the red lettering means and why some of my melds say +0? thanks...

[PetiteMalFleur]

Every item has a stat cap and your melds were over the cap.

[Skyler_Hawkins]

It's in red when someone affix the materia to the gear after the slots for materia is already taken up. The +0 just means someone wasted a materia try to add it to the gear. Each gear has a cap for each stay and if you go over that it does the +0

[Rydia_Lynn]

There a reference website for caps on items?

[Conradus]

Every item has a stat cap and your melds were over the cap.

It might be added that it warns about this when you're setting up the meld, before you actually meld the materia. You just didn't notice.

[KagatoAC]

There a reference website for caps on items?

Pretty sure the xivdb.com site has most of them in the comments section of the items

[Risvertasashi]

Usually the stat cap is somewhere around the highest stat on the item. Also:

It might be added that it warns about this when you're setting up the meld, before you actually meld the materia. You just didn't notice.

Keep an eye out on the meld screen, it will tell you if you'll hit the cap with your current meld.

[Urthdigger]

Ok, first off the cap for a given stat is based on the item level of the gear and the slot. Second, the cap is based on the TOTAL stats, INCLUDING THOSE ALREADY PRESENT. Third, high-quality crafted items are usually at or near the stat cap for all stats present on the item.

This means two things: First off, that adding materia for stats already on the item tends to not work. This is why stat materia is so cheap, any item made for your class is already going to have the stats you care about capped. Secondly, this means you can use the base stats on one item to find out the stat caps for other ones. For example, an HQ Tourmaline ring has 5 piety. This means you can likely add +5 piety to a Rubellite Ring (Same slot, same item level, but no base piety).

This does lead into something else. You'll notice the cheap materia is fairly useless. What does matter are secondary stats such as determination, crit, and such. And these can be expensive. They're commonly used either on endgame gear to make sure every piece of gear is capped on some desirable stat (usually determination or crit) or used in building the stats for the Novus phase of a relic weapon (again, usually determination and crit, but plenty of others are used). These materia can be VERY expensive. So, as a result it's probably best not to worry about materia unless it's for a piece you're unlikely to replace anytime soon, AKA making best-in-slot endgame gear.