Just before 8pm, a woman was assaulted at a bus stop on Edinburgh Road before a gold-framed Apple Watch with a pink wrist strap that she was wearing was stolen.
The incident came after she intervened when she saw a group of six to eight boys harassing a member of the public.
The group were described as being between 12 and 14 years old, who were white males, between 5ft 4ins and 5ft 8ins tall and wearing dark jackets.
If you witnessed a group of boys on Edinburgh Road around that time, we would like to hear from you.
Officers are particularly keen to hear from the member of the public who was being harassed by the youths prior to the robbery.
Anyone with information should call 101, quoting reference 44190405778.