Monika,
What you have may be a garnet, ruby, tourmaline, spinel, red beryl
or other red stone. It’s not hard to separate garnet from ruby , but
without some gem testing instruments and the knowledge of how to use
them there is really no way for you to tell. One instrument you
could use is a polariscope. You can jury rig one out of a couple of
polaroid lenses from a pair of sunglasses. Having almost unlimited
faith in the powers of Google, I suspect if you were to google the
word" polariscope" you could come up with a pretty good description
of how to make and use one. Watch out though! This gemology stuff
can be addicting to some people! If you don’t want to there may be a
rock club in your area, you might contact someone from the club and
ask if there is someone they know who can help. The easiest way of
course would be to take them to a gemologist.
Jerry in Kodiak