rough diamond 
noun
1An uncut diamond.Russia will supply 30,000 carats of rough diamonds for jewellery and 1 million carats of technical diamonds....
- The domestic diamond industry may soon get rough diamonds directly from African countries.
- The venture is a first for the diamond industry, where the world of diamond mining, which produces rough diamonds, and the world of jewellery retailing have historically remained very far apart.
1.1British A person who is generally of good character but lacks manners, education, or style: my grandfather was a bit of a rough diamond...
- Exuding coarse manners, she's every inch a rough diamond.
- I think he is a good soul but he's a rough diamond.
- I do not think that the defendant would object if I describe him as a rough diamond.
- red sable
- red sallow
- red sally
- red salmon
- red sandal tree
- red sandalwood
- red sanders
- red sanderswood
- red sander'swood
- red sauce
- red scale
- red scallop
- red schorl
- Red Sea
- red-sear
- red seaweed
- red-sensitive
- red setter
- red-shafted flicker
- redshank
- red shift
- redshirt
- red-short
- red-shortness
- red-shouldered