Officials said three suspects walked into Tala Jewelry on the 1300 block of Montana Avenue just before 5 p.m. At least one handgun was shown.
Santa Monica police officers spotted the robbers as they took off. There was a short pursuit before the suspects crashed their vehicle on the 3300 block of Exposition Boulevard.
The three suspects ran off. Authorities found two of them in a garage and arrested them. The third suspect remained at large.
Anyone with information about the robbery was asked to call Santa Monica police at (310) 458-8491.