Miniature painting Mary Queen of Scots signed a. Renoir

Miniature painting of Mary Queen of Scots with metal frame and pull out stand. Signature on side a. Renoir. Measures H- 5.50"x W- 4.25".  Several years ago I had sent pictures to Christie's Auction House. I was informed who the picture looked like and possibly was done when he was an apprentice, however difficult to tell via pictures. She informed me that I could send overseas for proper viewing which I did not.  I would appreciate any information on approximate age picture/ frame looks like etc...  Thanks!