The first production run of the Epiphone guitar named "Coronet" was in 1958, a year after Gibson, USA had bought the Epiphone company. The original design for the Coronet was planned to be released under the Gibson brand, bearing the model name Moderne. Though for reasons known only to Gibson, the model was renamed and released as an Epiphone brand guitar.
The Coronet was actually half of a two-part model line. The big brother to the Coronet was called the Crestwood. The differences between the Crestwood and the Coronet were numerous, though the essential design and appearance was actually quite similar. The Crestwood had more features and better hardware. The Coronet had only one pickup to the Crestwood's pair. The price of a new Coronet at the time was around $120.00, and was probably one of the best values in terms of price vs. performance available anywhere.
The design of the Crestwood and Coronet was an amalgamation of several stylistic elements from other popular guitars. The body was shaped roughly like a Telecaster, though it featured the symmetrical double cutaway similar to a Gibson SG, but with rounded horns rather than the SG's famous pointy "devil" horns. The symmetry of the cutaways has been played with over the years, so it is possible to find asymmetrical cutaways. Over time, each revision of the Coronet body made it slimmer and slimmer.
Originally the Coronet came with a single Epiphone New York pickup in the treble position. In 1959 Epiphone began shipping new Coronets with a p-90 pickup and began offering the Coronet with it's signature cherry red finish. These models are the most sought-after by collectors and enthusiasts, and are regularly valued in the 1000+-dollar range. Not bad for the "budget" model.
In the 1970s, production of the Coronet came to a halt when Epiphone packed up and left it's facilities in Kalamazoo, Michigan to move overseas, where it would eventually become known as Gibson's line of cheap clones.
There was a short run of Coronets in the late 1990s, which were made in Korea. These featured OBL model pickups, a single coil in the neck position and a humbucker in the bridge position, with a pull-out tone knob to tap the humbucker. As was the case with the original Coronet, the hardware and style of the Coronet was varied through this short run. Some had six-on-a-side batwing-shaped headstocks, while others had more classic 3-on-a-side Gibson-style headstocks. Common paintjobs were red and blue, though they were opaque metallic-flecked paint, as was popular in the time, rather than the transparent colored wood stain of the original Coronets.
After a short run, Epiphone realized the Coronet was not what the kids of the time were looking for. The musical scene of the day was run by heavy metal and grunge music, which was not suited well by the tactfully quirky looks of the Coronet. The kids only wanted what they saw on MTV, and the mature adult players generally shy away from the Epiphone brand, due to its reputation as cheap knock-off versions of real Gibson guitars. Thus ended the lifetime of the Coronet.
The first Coronets were the first solid body electric guitars made by Epiphone as a part of Gibson. The last Coronets were made in 1997, and remain one of the very few models of Gibson-era Epiphone guitars that were not directly modeled after a specific model from the Gibson brand.
Note: There is, to my knowlege, no authortative source of information about the history of the Epiphone Coronet. The above writeup is the best account I could gather, through various fragmented, and sometimes blatantly conflicting sources, including discussions with music store owners, online discussions with strangers via web forums and multiple websites in varying stages of neglect. If you have better or more accurate info, please put it in this node. I'm no expert, I just like my guitar.