This changed in the late 1920s, when they began producing some better instruments with the Harmony name on them.I would guess your ukulele was made in the late 1920s.It is in quite good condition, although it sports a few scratches on the neck and body. You have a very nice looking Style 2 ukulele manufactured by the CF Martin Co of Nazareth, Pennsylvania. Based on the particular style of tuning pegs (manufactured by Kluson), I would estimate that it was made in the late 1940s or early 1950s.Martin ukuleles are considered by many to be the best ukuleles made, so they are desirable to players and collectors alike. At this time The Style 2 ukulele was one model from the top of the Martin ukulele line, above the Style 0 an Style 1, but below the "professional" model, the Style 3.
It is obviously quite old, well made, and, judging by the scarcity of available information about it, pretty rare. I have seen other Harmony ukuleles with some of the same characteristics, but I haven't seen another exactly like yours.It was probably one of their top-of-the-line instruments.It looks to be made of some very nice quality mahogany.It says "Senorita genuine Hawaiian Ukulele" on the label, looks like it might be mahogany.Has bakelite tuner knobs, the seller tells me its from the 40's.They were out of ukulele manufacturing altogether by 1929. This is somewhere between what most people today call concert size (about 23" overall) and tenor size (about 26" overall).The Washburn name was used on L&H's top quality instruments.I would guess these were made in the teens or the early 1920s at the latest.I am very curious about the 2nd label you mention in your ukulele - this could help solve the mystery.The shape of the bridge on your ukulele is typical of Harmony ukuleles made in this time period.When I first saw the label photo I thought it was a more recent ukulele, but the "Standard Approved" mention makes me think it is older.