Take care of false 'red coral'. Most pieces are good, but a lot of fake may be found. I'd rather avoid thinking the real red coral is from Sardinia: most of it comes from the Chefarines islands, a Spanish enclave, close to Melilla, on the Moroccan northern coast of Mediterranean. Red coral is almost disappeared from Sardinia, due to over capture.
The local sellers hounding you on the beach with offers of sarongs and other merchandise. Some of it looks nice but the quality of items can be poor and the sellers can be incredibly persistent and quite annoying.