It happened at a store in the Fairview Pointe-Claire shopping centre at about 8 p.m.
Const. Eric Labad of Montreal police said the suspects used pepper spray to get past the security guard.
That Birks location was robbed in November and in 2010 by thieves using pepper spray. It had been the target of robbers in the past as well.
Labad said one of the suspects was wearing a black hoodie and grey coat, while the other wore a yellow hoodie and grey pants.
Police are asking anyone with information to call the Info-Crime line.