STERLING MID CENTURY MOD - 925 silver brooch with red stone

Vintage sterling silver, mid century mod design brooch pin featuring sterling silver with patina the pin mechanism on back is small it is in good working condition. I don’t know what type of Redstone it is. It looks like glass, but again I’m unclear as to what kind of stone? I am not going to polish this jewelry I will leave the polishing to the new owner if you are not, familiar with buying vintage jewelry please pick up some vintage jewelry books, learn about vintage jewelry prior to purchasing vintage jewelry. Thank you.