Sunstones are aventurescent (sparkly) natural stones in the
feldspar group. They are usually orange or red.
The typical orange cabochon type is usually oligoclase feldspar.
The reddish (some gray, bluish and green banding possible)
faceted variety is labradorite feldspar. The sheen is caused by
hematite or goethite inclusions (oligoclase variety) or just
hematite (labradorite variety). The labradorite varieties tend to
be more expensive, i.e., Oregon sunstone (reds & greens). The
bright orange Sri Lankan oligoclase sunstones can range a lot in
price, but I have seen 10 x 12 cabs go for $.50 to $3.00 each.
You should shop around to get a more accurate idea of prices. The
book, Color Encyclopedia of Gemstones, by Joel E. Arem, Ph.D.,
FGA goes into great detail. The Gem Reference Guide, GIA
discusses it as well. I’m sure there are plenty more books
about it. Hope this helps Later, Arthur