Black cumin (Bunium persicum or Bunium bulbocastanum) seeds, with a U.S. penny (one-cent coin) at left, for comparison. Photo taken in Kent, Ohio with a Panasonic Lumix digital camera (model DMC-LS75). Basil seeds purchased in a northeast Ohio-area Indian grocery store. These seeds are called kala jeera in India.
Using coins for scale is discouraged as it will require people unfamiliar with them to look up the dimensions or guess, both of which defeat the purpose of the object in the first place. Coins can also reinforce a geographical bias, and some coins' designs are copyrighted.
Ideally, a photograph should include a ruler with the subject (example) or an added scale marking.
SI ("metric") units are the most commonly used worldwide (see meter and centimeter).
== Summary == {{Information |Description=Black cumin (''Bunium persicum'') seeds, with a U.S. penny (one-cent coin) at left, for comparison. Photo taken in Kent, Ohio with a Panasonic Lumix digital camera (model DMC-LS75). Basil seeds purchased in a n