Khi chua biet vien da la kim cuong that hay gia, ban muon kiem tra so bo chung thi ban co the su dung thiet bi thu xoan (chich vao be mat vien da ma phat ra tieng keu thi la da that, khong keu la da gia) nhung loai thiet bi nay khong phat hien duoc loai da Moissanite (mot loai da gia kim cuong rat tinh vi, rat dep, rat giong kim cuong that).
Hoac ban co the ke 2 duong thang song song, cach nhau 3 mm, tren mot to giay trang, sau do dat vien da len 2 duong thang nay. Neu chung ta nhin qua vien da ma thay duoc 2 duong thang nay nam ben duoi vien da thi day la da gia kim cuong, con neu chung ta khong the nhin thay 2 duong thang nay ben duoi vien da, thi do co the la kim cuong that.
Nhung cach kiem tra tren chi la nhung nhan dinh ban dau vi cac phuong phap do van con co nhung sai so (khach quan lan chu quan) dan den ket luan sai ve vien da. De chac chac rang vien da do la kim cuong that hay gia thi ban nen nho den cac chuyen vien giam dinh da quy hay cac to chuc chuyen giam dinh da quy (nhu Cong ty TNHH Giam Dinh Rong Vang - SJC cua chung toi chang han) xac dinh, chung nhan cho chung.