Not a red stone at all, it is a golden-tan color, so that eliminates the garnet or ruby ( unless they have a gold variety). I showed this to a gemologist and he speculated either a topaz or opal, but thought those stones were rather soft to be mounted in a sword handle.
The stone appears to be a Scottish yellow Cairngorm stone.
If the gemologist said it was not garnet or ruby
The next best guess would be a Quartz variety, most prolific
I had not heard of the "Scottish Cairngorm", that is also a quartz, smoky, local to and given Scottish name
Plenty of smoky quartz all over eastern US.
Quartz is a crystalline rock or mineral composed of silicon dioxide. Quartz is the
second most common mineral in the Earth's continental crust and found in all types of geological environment. There are 49 variety's, a number of which are gemstones, some of which are very beautiful and very rare. Origin of name from Saxon word Querkluftertz = cross-vein ore.
Colour: colourless, white, gray, yellow to brown to black, violet, pink
Hardness: 7
coloring of each quartz gemstone usually depends upon the amount of iron (ferrous oxide) that fused with the quartz and under how much heat
Smoky quartz, is common and can be yellow, brown, to orange
or Citrine I don't know if 1860 jewelers were heating stones, probably were
Citrine is a form of quartz with ferric iron impurities and is
rarely found naturally. Origin of name from the French word "citron" meaning lemon. Also called citrine quartz. Most commercial citrine is in fact heat treated amethyst or smoky quartz. Brazil is the leading producer of naturally mined citrine.
Colour: the different shades range from yellow, gold, orange brown shades of transparent quartz.
Hardness:7
N.B. Citrine and Amethyst are the exact same minerals, the only difference is the level of oxidation of the iron contained in the mineral. As this can be done artificially by heat or irradiation a large majority of Citrine sold today is heat treated amethyst. There are currently no scientific ways to determine if Citrine was changed artificially.
Bringing the