A: String Orchestra
B: Flute, violin, 'cello and harp
Artists are uncredited on this pressing
Side R: mx. 1261-A was recorded in New York, NY between September 9 and September 16, 1912. Originally issued on Edison 50013-R in May 1913. Later pressings of Edison 50052 use mx. 3812, recorded May 24, 1915.
Side L: mx. 2789-C was recorded in New York, NY between January and February 1914.
Dating Edison discs is like working a puzzle. The Old Man kept titles in his catalog for years and years, replacing label styles as older sub-master molds wore out, even if this applied to only one side of the disc. One excellent resource for dating Edison disc records is "Collector's Guide to Edison Records" by George A. Copeland and Michael W. Sherman. I've attempted to summarize some of the key points of this work in my write-up on the Edison Records label page on Discogs. However, I do agree with @slholzer that the process of properly identifying these discs can be a time-consuming endeavor. Still, I find it to be an enjoyable and rewarding activity.
It is quite easy to get very confused trying to sort out the release history of early Edison discs, particularly when you only have photos to work form. As may be noted from the illustrated examplar, the issue number does not appear on the labels of the early engraved versions. Neither does the matrix number. (The issue number (with side designation) would eventually be incorporated into the engraved labels. By 1915, paper labels would also include the matrix number. ) A paper-label of this disc can be viewed on the discogs site, which allows us to determine that that version used mxs 3812 and 2789 (recorded May 1915 and Jan-Feb. 1914, respectively,) and must therefore, have been issued no earlier than May, 1915. As I noted previously, the original version of Ed 50052 was reported by Wile as issued in August 1913, and must of necessity have used mxs 1261 and 1053. Assuming that the illustrated disc has been confirmed by the contributor to use mxs 1261 and 2789, it would logically have to have been issued no earlier than 1914. It's engraved label marks it as an earlier pressing than the discogs paper label.
All of the above poses a practical problem: so far we have at least three discs bearing the same issue number, with three different combinations of mx numbers. The Trusound website indicates that at least two takes were issued of some of the mxs used on Ed 50052. There may be more pairings extant. Brian Rust and Ray Wile both support the notion that Edison likely issued all available takes of his records as a practical means of keeping up with the demands of record production. Arguably, every available pairing of the matrices is a different discographical object. with a different release date, even if we don't know what they were. A single listing entry iwill be challenged to document all of them without copious and potentially confusing notes. More than a few of your subscribers will likely find it beyond their skill level to properly identify the records they have in order to correctly place them in separate listings.
Thank you for the additional information about this disc, @slholzer. Upon re-reading the notes concerning the re-recorded L side matrix 2789, the release date for this disc should be 1914, rather than 1913.[Now fixed! Mod.]
Per Raymond R. Wile's "Edison Disc Recordings, Book I of II" this disc underwent the pairing of sides process in the Edison labs in July, 1913 and was released for sale in August, 1913. That version must of necessity have used mx 1261-A on the R side and mx 1053 on the L side. Per Wile, later versions of Ed 50052 used mx 3812 on the R side and 2789 on the L, both of which were recorded after the original issue date of the disc. Wile does not provide release dates for the later pressings. It may be that such information is simply not available.
Per Wile, the first 50 Edison Diamond Discs were made for use as machine demo discs and were pressed in small numbers. All but Ed 50001 and 50045 were dis-continued by July 1913. Ed 50013, referred to in the notes, would have been one of these. The L side of the illustrated disc would have been variously issued on demo discs Ed 50020, 50022 and 50026. All would be quite rare and most likely in heavily-used condition if you found them. If you are looking for either of these sides, you would do better to look for Ed 50052..
The tracks used on the demo discs were re-pressed on the next 24 numbers, although not with the same pairings of sides as the demo discs. This makes the illustrated disc one of the first Edisons made for general distribution to the public.