This is a lovely 925 Silver Black Onyx Necklace.  In a highly polished Cabouchon Cut Design.  It is Rhodium Plated on to 925 Sterling Silver.  The Pendant comes supplied on a Rhodium Plated 925 Sterling Silver Chain.   In a Curb Chain Design and measures 18 inches in length. 
Measuring approx 3 cm including the bale x 1.4 cm at its widest.  
Comes boxed and would make a lovely Gift.