Mitered Purfling
It's a small thing
Instrument makers often like to show off their attention to detail and workmanship by having the purfling meet at the corners, like a picture frame:
The little angles where the purfling lines meet are called "miters" if they form these nice little frames.
Here's another instrument with mitered purflings:
And, here's one without:
Most factory made steel string guitars do not have mitered purfling.
Here's an elevated fingerrest with mitered purfling:
While mitered purfling may be considered optional on a steel string guitar back, a raised fingerrest like this one virtually always has mitered purfling. Go figure. . .