English: Polyphant cresset stone or lamp, circular in plan and sub-square in profile, with a hollowed out, semi-circular interior. The word 'cresset' is derived from the old French 'craicet', 'craisset' or 'cresset', a cup of metal or other material fastened to a pole to form a portable lantern. A 'cresset stone' was a flat stone with cup-shaped hollows, each being used to hold a quantity of tallow and a wick, which were burned to produce light. This was a common method of lighting churches in medieval times. It was also common to find such stones near doorways or corners where people had to frequently pass each other.

Polyphant stone is a soft metamorphic rock type, similar to talc, that is predominantly blue grey with green patches, and white and brown veins. Polyphant is still worked near Lewannick on a small scale for sculptural, monumental, decorative and dimensional purposes, and has been used for ornamental carvings since the 11th century.

Penhallurick (1986) refers to another 'small hollow basin of Polyphant stone appearing like a crucible' on page 207.

Adams (1967) illustrates several local examples on page 55, Fig.13, but the two cresset stones that are most like the one recorded here are No.4, from Chun, and No.8 from Trethevy chapel at Tintagel, not far from the findspot.

Hague (1968) discusses the larger cresset stone basin, with a round rope wick hole, which was used as a lighthouse lantern on St. Michael's Mount from the 14th century, on pages 64-5.

Ottaway & Rogers (2002) illustrate a similar individual stone lamp on page 2858, Fig.1435, No.11033, which is dated to the mid 13th century.