The diameter given in the above description, is that provided in the CNG listing. The vertical axis of this coin is 16.96mm. In correspondence, CNG observe that: "Diameters are measured by CNG from 9' to 3'. This will give some degree of variability for coins like darics, that are more elongated along the vertical axis". The comment by CNG was provided in response to my question as to how they measure the diameter of an ancient coin. In asking this question, it was noted that I had looked at the 500 similar coins in the CNG archives and found a very large variability of the diameter from 11mm to 16.5mm. Auction houses and dealers have a range of "conventions" in indicating the diameter of a coin, including: 1. A single measurement from 9 to 3; 2. A single measurement of the maximum width; 3. A single measurement that is the average width of the coin; and, 4.A range measurement of narrowest to widest (such as 13.00 -16.96mm). A photograph can be misleading to potential buyers, researchers and scholars and, is still misleading when the photo is accompanied by a single measurement that records the diameter without indicating how that diameter was derived. The 'thickness"', or profile depth, of the coin is also prone to large variability and is a useful piece of information for coins of this series. The reasons surrounding this variability are open to speculation, but to get an appreciation of the coins in this series without physically being in their presence, a better convention is called for in recording measurement data.