stall

Stal Collective term for chemically precipitated mineral material formed in a cave or caves. As a collective term, "stal" has no plural. Lowe and Waltham consider "stal" to be a colloquial term. Cf. speleothem.

http://www.gly.uga.edu/speleoatlas/SAglossary1.html



http://www.google.co.uk/search?q=define: Stal &hl=ar&oi=defi...

اي القص او القطع لقطعة الحجر الكريم التي هي على شكل الحليمات العليا او الحليمات السفلية والمربعة

I looked up "Stal" on Google and found it consistently used on one site that deals with jewelry. Fpr example, one title states: stal and cubic zirconia, but when you go down further and look at the details, under gemstone it says: crystal. I suspect that these are synthetically manufactured crystals, and for this reason they are using "stal" in the title instead of just saying "crystal" outright. In this case I would transliterate the word "crystal" in its entirety rather than transliterating "stal" otherwise the reader will have no idea what you are talking about. The other option is to use بلورة however, I think that this will be understood to be a natural crystal as opposed to a synthetic one.