Ruby + Sapphire is my take on the tried and true ruby mod. It's been done time and time again, yet, I wasn't quite satisfied with any of them in particular, so I tried my hand at making my own.

Features:

New Armors and Tools crafted with Rubies and Sapphires- two new ores that spawn underground, at slightly higher levels than Diamonds.
The properties of Rubies and Sapphires are identical; this just gives you a choice between red or blue.
Experience Ore- a rare ore that drops a good amount of experience when broken; typically enough to boost you towards leveling up. It also has a faint light level and nice animated texture.
Save your precious Diamonds- you can craft a vanilla Jukebox using either a Ruby or a Sapphire in place of a Diamond. Groovy!

The tools this mod adds are at Diamond mining level (meaning you can mine obsidian, etc), but with much less durability than Diamond tools.

The Armor falls between Iron and Diamond in terms of defense. A full set will give 9/10 armor notches (Iron gives you 7 1/2). The armor sets also have toughness, like Diamond Armor, but not as much (each piece only has +0.5 toughness compared to Diamond's +2 toughness).

Unlike most vanilla ores, Rubies, Sapphires, and Experience Deposits do not spawn in clusters/groups; only on their own. With the wider range of levels they can spawn at, along with their not too ridiculously high rarity, they shouldn't be hard to find, but you also shouldn't be drowning in them.

In Version 1.1 spawn-rates have been tweaked (I started having an easier time finding Diamonds than Rubies, which wasn't my goal with this mod!).

Rubies and Sapphires will now spawn in small clusters.

My hope is that this mod will satisfy your desires of mining colorful, new ores and crafting unfamiliar tools and armor sets. I'd like to think this mod adds the bare minimum to be unique, but without going over-board adding too many unwanted extra features. Enjoy!

Update:

A spiritual successor to this mod is now available for Version 1.16.5: https://www.curseforge.com/minecraft/mc-mods/ruby-sapphire

Ruby + Sapphire + Experience Ore