An example of Queen Anne architecture as expressed in a commercial setting, the Diamond Block is one of only four buildings of this style in the district. Three stories in height, the building has two story oriel windows the full length of the façade, interrupted by balconies over an arched entrance. Built entirely of cut stone, its embellishments consist of periodic pilasters and a double row of corbeled stone dentils at the cornice.
Forced into the shape of a triangle by the less than stringent layout of streets, Sixth Avenue and Last Chance Gulch (yes, that's a street name) in particular, the two rear sides of the building are plain, unadorned brick and stone. An interesting aspect of the building is the false front at the west end of the façade. In order to not break up the continuity of the façade because of the lack of building behind the west end, it becomes a false front behind the final two oriel windows.
One of the news articles we found concerning the Diamond Block is the following short article from 1890, dealing with the reopening of the drug store in the building.
DIAMOND BLOCK DRUG STORE
A Convenient Place for West Siders Again Open.
The Helena Independent | December 07, 1890, Morning, Page 2
Mr. F. C. Sutphen, formerly with H. M. Parchen & Co., has purchased the stock and fixtures of the Max Behrens' drug store on Sixth avenue, in the Diamond block. Mr. Sutphen is a registered pharmacist and thoroughly conversant with all the details of the drug business. The store he has put in excellent shape, a new line of drugs purchased, while the stock of fancy goods as large and complete as is found in any retail drug store. Of perfumes, standard goods only are kept in stock, while there is a large line of Imported and domestic soap. In fine cutlery the assortment is complete as well as the stock of brushes for ail purposes.
Particular attention will be paid to the prescription department, and patrons will find no difficulty in having them filled at any hour of the day or night.
From The Helena Independent