Eric
Both of us are filtering the factual evidence through our own particular mindsets. The factual details are the same, but the interpretation is different.
Sophie of Greece and Marie of Rumania were first cousins, but seem not to have been particular friends. Maybe they were just too different in tmperament. In any case, as I have already said, being related does not of itself mean you have to be friends.
To my mind (though not to yours, clearly), it is not really surprising that Sophie may have had other things on her mind besides jewellery at the time George and Elizabeth married. Her husband had only just been restored to the Greek throne, and doubtless she was grieving for Alexander, who had died only four months earlier. Her daughter Helen married Carol only 11 days later. Given his past history (the Lambrino marriage) and the possibility that Helen was already pregnant (presumably by Carol - I am not aware of any doubts ever being raised about Michael's paternity), plus Marie's own scandalous history, plus the possibility that Sophie was aware of Elizabeth's recent affair with Frank Rattigan, it seems unsurpring that Sophie was less than enthusiastic about the marriage with Elizabeth (or indeed Helen's marriage to Carol). By the standards of the 1920s, one would have to be an unusually forgiving soul to put aside all that. And perhaps Carol's subsequent behaviour towards Helen coloured Sophie's attitude to Elizabeth? I don't know, but I find it rather sweeping to condemn Sophie as 'mean' and 'stingy'.
Can you post the3 relevant excerpts from Elizabeth's letters to her mother.
Ann