Garnet
There are many species of garnets, each with a different chemical composition. The most common is the classic red almandine. Andradites have a dispersion even higher than diamonds, grossulars can be just about any color, but not blue, hyrdrogrossulars are opaque, pyropes are comparable to rubies, spessartites are orange, and uvarovites are emerald-like.
Where it's Found: All over the world.
Mohs Hardness Scale: 6.5-7.5
Jasper
Jasper is an opaque fine-grained variety of chalcedony that comes in vibrant colors and unique patterns. There are many types of jaspers. Ocean jasper, picture jasper, leopard jasper, zebra jasper, biggs jasper, and bumblebee jasper are just a few of these.
Where it's Found: All over the world.
Mohs Hardness Scale: 6.5-7
Rhodochrosite
Rhodochrosite is the national stone of Argentina. It ranges from pink to red and is usually opaque with banded patterning, but can also be translucent. It is often confused with rhodonite, which can have similar color and patterning in addition to a similar name.
Where it's Found: Argentina, Colorado and Montana in the US, Mexico, Peru, South Africa, Canada, Japan, Khazakstan, and Namibia.
Mohs Hardness Scale: 3.5-4
Ruby
Rubies are the red variety of corundum. All other colors of corundum are considered to be sapphires. Pinkish shades are often up for debate. People usually think of the gemmy rubies, but they can also be opaque. The value of a ruby is largely determined by its size, color, and origin. Myanmar sources some of the most valuable rubies, including the coveted "Pigeon Blood" ruby.
Where it's Found: Myanmar, Sri Lanka, Thailand, Cambodia, Madagascar, Kenya, Tanzania, Mozambique, Afghanistan, Nepal, and Vietnam.
Mohs Hardness Scale: 9