The most common and most likely answer to this crossword clue is the 5 letter word TOPAZ
I've seen this crossword clue in Independent
T
O
P
A
Z
More clues leading to the result TOPAZ
- Hummer to reverse move quickly
- Best characters, first and last, producing a gem
- Gem of a high note at last
- Stone to sacrifice the Spanish in Andean capital
- Best street maps of a dark yellow colour
- Best street guideās a gem
- Turn over and force up stone
- Destroy ring with opening for tiny round gemstone
- Best article on unknown stone
- Stone to kill, lobbed over
Buddy explains!

The straight part
We know that "(precious) stone" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case (precious) stone = topaz.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TOPAZ mean?
TOPAZ noun- A silicate mineral of aluminium and fluorine, usually tinted by impurities.
- An often clear, yellowish-brown gemstone cut from this.
- A yellowish-brown color, like that of the gemstone.
- (British India) A black Catholic soldier in the British Army.
- Of a yellowish-brown color, like that of the gemstone.