A question recently came up about Sarah Coventry patents...so I did a little research. I don't have any direct knowledge from the company, but here is what I found (as of October 2008) through googling and patent searches..
The general sense of what I could find was that they did NOT have design patents for their jewelry. I did find some utility patents.
In Lillian Baker's book titled "Fifty Years of Collectible Fashion Jewelry 1925-1975", she states that neither Emmons or Sarah Coventry designed or manufactured their own jewelry.
Also per Ms Baker's book (and other sources), Emmons was incorporated in 1949 and Sarah Coventry shortly after. This does fall into the time frame that designs were often patented. However, so far, I have not found any jewelry design patents assigned to "Emmons", "Sarah Coventry", or "C. H. Stuart" (the parent company)
The utiltiy patents that I found were also not in this time frame. There were a number of early patents by C.W. Stuart (C.H.'s father) and C.H. Stuart for items relating to their plant nursery business and C.H.'s chemistry and cosmetics work. By early I mean as far back as 1892 (for C.W.) I've listed some of the patents below.
The 1960's and later patents
The patents that I found in the 1960's and later, were related to the jewelry business. I'll desribe those first, with the older patents below for reference (since they aren't really jewelry related - I just found it an interesting part of their history.)
Patent # 3688520 - 1972 - An ornamental finger ring for two adjacent fingers including a removable ornament. 
Patent # 4082390 - 1976 - A convertible tray cabinet that can be used as a saleman's case for stacked jewelry trays
Patent #s 3234756 and 3336427 - filed in 1961 granted in 1966 and 1967- relates to an earring construction and more specifically to an earring paddle having a hollow resilient pad bonded thereto and method for making the same. 
Now just for fun, some of the older history and patents.
I found some very detailed info on the company and family on this website: http://www.house-of-francheska.co.uk/vintagesarah.htm - it is really worth a read!
C. W. Stuart
They describe that in 1852 Charles W. Stuart arrived in Newark, New York and started a small farm, selling fruit trees door to door. This became the C.W. Stuart Nursery. He also established several other nursery firms, one called Emmons Nursery.
Patents for C.W. (or the C.W. Stuart Company)
Patent # 485358 - 1892 - A ruling pen (as in writing device)
Patent # 790760 - 1904 - For a Hoe or Weeder
Design Patent # 157218 and 157217 (patented to the company) - 1948 - Landscape Planning Ruler
Plant Patent #1529 - 1956 - A Rose plant (note: there are also other Rose plant patents)
There may certainly be more patents, the above were found with a quick search.
C.H. Stuart
C.W. Stuart died in 1923 but his son Charles H. (C.H.) Stuart had taken over years before. C.H. was trained as a chemist and began experimenting with extracts, marketing them using a new term "direct selling". Eventually, several direct selling companies were established under C.H. Stuart that sold cosmetics, household goods, silverware and china.
Patents for C.H. Stuart or the company (note: there may be other, this was just a quick search)
Patent # 786067 - 1904 - Typewriter Platen
Patent # 1005668 - 1910 - Collapsible Tube
Patent # 1852708 - 1929 - Patent for a Safety Razor
Patent # 2003562 - 1933 - Fluid dispensing Device
Patent # 3380307 - 1968 - Lid Scoop
Patent # 3230755 - 1966 - Apparatus for bending material
In 1949 it was decided to market costume jewelry using a plan that had worked with china and silverware. So the Emmons and Sarah Coventry companies came into existense