Question

Why a real diamond does not show in a x-ray ???

Answer 1

Answer:

X-rays can be used in various diffraction techniques to study the crystal structure of diamond - or just about any other - in the laboratory. Most of the myths about diamonds not showing up on X-rays, however, are more concerned with the sort of X-ray photographs taken in hospitals and airports.

Objects show up brightly on X-ray photographs if they block a high proportion of incoming X-rays. A material’s ability to block (technically, scatter) X-rays depends on several factors, but the most important is atomic number (Z). A high-Z material scatters a high proportion of incident X-rays and so shows up brightly in X-ray photographs.

Medical X-rays are set up to differentiate between skin and tissue - which are mainly composed of carbon (Z = 6), hydrogen (Z = 1), oxygen (Z = 8) and nitrogen (Z = 7) - and bone - which also contains calcium (Z = 20) and phosphorus (Z = 15). Metals like iron (Z = 26) and gold (Z = 79) therefore show up very brightly.

Diamond is composed entirely of carbon (Z = 6). It therefore does not show up very brightly on many medical X-rays. One of the common diamond replacements is cubic zirconia, which contains zirconium (Z = 40) and therefore shows up much more strongly.