It seems likely that Sathya Sai Baba never gave anyone a genuine diamond

All proof is lacking,  which would be easy to obtain from any fully accredited diamond expert. Yet none has ever been forthcoming! When Queen Margarethe of Denmark’s personal jeweler, Mr. P. Hertz of Copenhagen, examined my supposed ‘green diamond ring’, he said he could not be entirely sure that the green gem (about 5-6 carats) was a fake unless he could open the 18 carat gold casing in which it was set so that the rear of the stone was concealed. When I allowed this, he found the stone to be a synthetic sapphire (originally worth Prof. Keith Crichlow with bogus 'diamond'about US $10 or so at the time in India – or perhaps even less, since such stones are now being advertised on the Internet for tiny sums). It’s brightness had been enhanced by a piece of greenish tinfoil behind the stone, protected by the rear casing. (The assay was photographed, see here) The tinfoil was arranged so that the appearance of a vague silhouette of a head would appear in the stone when seen from certain angles (as seen in the images above). One can just about imagine it is Sai Baba’s fuzzy head. (However, devotees are experts at imagining he is everywhere and miraculously omnipresent etc. which influenced my mind for some time until I studied how it was a reproducible effect with the correct shading and light.

That the stone is a fake conflicts totally with what Sathya Sai Baba let us understand about it when he gave it to me at an interview on Dec. 23'rd, 1986. It was something for which I never asked, but to refuse in that situation was unthinkable. No more, however! Devotees said it was such a great honour and - until that time - very few persons had been given such large 'green diamond' rings. Among those few who had were: 1) the former and subsequent International Chairmen of the Sathya Sai Organisation, Mr. Indulal Shah and Dr. M. Goldstein 2) The Head of Administration at the Vidyagiri ‘deemed’ University - Mr. Kanhaia Jee, 3) Mr. Victor Kanu, who runs an authoritarian Sai school in Zambia, and 4) Mr. Robert Bruce 5) Professor Keith Crichlow 6) Mr. Antonio Craxi (Apropos, Mrs. Craxi stated the opinion that green rings are "power rings”. But her husband was unable to help keep his brother, Bettino Craxi, in power, not with the help of his ring (nor with their Mafia connections, for that matter.) Mr. B. Craxi, who visited Sathya Sai Baba in Puttaparthi while he was Italy's Prime Minister, died recently as a criminal in exile in Tunis, fleeing a conviction in Italy to about 18 years in prison plus massive multi-million dollar fines.

Another giveaway that these alleged “diamonds” are not real is the wear and tear they mostly show after being worn for a few years. I saw this on the green gemstone of Mrs. Maynard Ferguson, which was scratched so much (from washing up, she said) that it was very dull. Those green stones which are synthetic sapphires are, however, very hard and are less prone to damage being somewhere near as hard as diamonds. Diamonds NEVER scratch (unless sometimes under much pressure by other diamonds), but they can chip and shatter if hit hard, and tiny bits can fracture off around the edges. (See documentation here).

Dr. Michael Goldstein’s ‘fake diamond’ ring plus  Robert Bruce with false 'diamond ring'  Dr. Michael Goldstein's bogus jewels  Rahm family cheap Sai Baba trinkets  Two views of ring given to R. Priddy