MARTPURA , 40km east of Banjarmasin, is famous for gems , especially diamonds, mined nearby at the village of Cempaka (except Fri). Orange bemos leave Banjarmasin's Terminal Km6 throughout the day (Rp1250) and terminate at Martapura's plaza. Even if you have no intention of buying, it's fascinating to look around the trays of diamonds, turquoise, tiger's-eye, topaz, amethysts and tektites, but don't deal with the hawkers unless you can tell coloured glass from the real thing; the nearby showrooms offer a more reliable place to shop. Martapura's single losmen refuses to take foreigners - the last bemos return to Banjarmasin after dark. Green "Mart-Cemp" minibuses depart regularly from Martapura's plaza for CEMPAKA (15min; Rp500), where a muddy, two-kilometre track leads past a monument to the diggings. Most of the excavations are worked entirely by hand: a hole in the ground marks a shaft with a human chain reaching down into the water 10m below.