I see another poster has recommended this but I feel obliged to point out that Colombo is more than just tea and biscuits - it is salgadinhos - Brazil's equivalent of dim sum, which are an absolute must for anyone wanting a culinary experience in Brazil - try bolinhos de bacalhau (fried salt cod balls) or rissole de camarão (prawn rissoles). The only place that arguably does them better than Colombo is Bar Bracarense (also recommended by another poster, but note it is in Leblon, not Ipanema - although the address is right).
Colombo is wonderful, but I feel a need to enlist potential tourists to the sacred cause, which is to persuade a narrow-minded management that they need to keep the ground floor cafe, with its belle epoque mirrors, open as a cafe for the general public and not simply close it off to tourist groups (usually multinationals) - which they have a bad habit of doing. Give the maitre a hard time if you find them doing this. You may thus have to stand at the bar.
Rua Dias Gonçalves as above, in the Centro.
Is this your business?