|Spinels comes in a wide variety of colors, with the deep red or bright pink being quite desirable. Similar to "ruby red" and caused by the same element chromium.
The spinel-group is a series of minerals with the same general crystalline structure but widely different chemical compositions. The aluminum-magnesium spinel is the one most cut as gemstones. It comes in many shades of red, pink, lavender, blue, green, brown and black.
Spinel can be grown in the laboratory and synthetics are available.
The first stone is a purple-red spinel (native cut - hence pineapple back), the second is a highly included pinkish spinel and the last a suite of small native cut pink square spinels.