The fruit of Euphorbia rhombifolia is a small, spherical, fleshy capsule, from green to brown in colour. It is about stalkless (sessile) and 3 mm in diameter.
These fruits or the remains of them were seen in August (Vlok and Schutte-Vlok, 2015; Shearing and Van Heerden, 2008; Gledhill, 1981; iNaturalist).