Black Diamond Strings 1890 to present Black Diamond Strings have been made in Florida USA since 1890.  The idea for including strings in this collection came from a request from antique dealer who was seeking information about old instruments he had come across.  One guitar had these old strings in the case:

Black Diamond Strings 1930s-40s

I referred them to Black Diamond and they were kind enough to provide the following comment: “It is hard to tell exactly the decade the vintage strings were made because they used the red envelope package for many, many years.  My wild guess would be 30’s or 40’s.” [Source: Black Diamond, email  29/9/2008]

When I started playing in the mid-1960s, these strings, with the same package design as in your photos, were the “least common denominator” as the cheapest and most widely distributed. For guitar, they only came in one gauge. The brand name came from the synthetic diamond dies the wire was drawn through. I believe at different times, they were made in Chicago and in East Brunswick, New Jersey by the National Musical String Company, which may have had an affiliation with the Harmony Company. I think they were probably still available with the same design into the early 1970s or maybe even later.

The attached photo (below) is of an old unopened package from my old days. Note the 5-digit postal “Zip Code” in the company address. That system was introduced around 1962 or 1963, and remains in use today. Earlier USA postal codes were two digits between the city and state, but the lack of either code on a product label doesn’t necessarily have anything to do with the date of the item thanks for your great website!” [Source: Bill Ruxton, Millersville, Maryland, USA WUfoo, email 9/3/2015]