At roughly 1.6 metres long and just under 0.7 metres wide, it is not a small object, yet it is easy to overlook among the other recumbent slabs clustered near the north-west angle of the church. What makes it worth a second glance is what lies beneath the surface: an inscription that only reveals itself under a strong raking light, the kind that comes low and sideways in the early morning or late afternoon.

The slab carries a Latin cross set inside a rectangular frame, the cross arms finished with half-round ends and a round centre, all rendered in incised double lines. Around or alongside this design, scholarship has gradually teased out a short Early Medieval inscription: OROIT AR DIARMAIT, an Old Irish phrase meaning "a prayer for Diarmait". This formula, asking those who pass by to offer up a prayer for the named person, appears on commemorative slabs across early Christian Ireland; it is one of the most direct surviving forms of personal devotion from the period, addressed not to posterity in any grand sense but simply to whoever might be standing there. The scholar R. A. S. Macalister recorded the slab in his 1949 Corpus Inscriptionum Insularum Celticarum, noting that it had already been badly damaged by foot traffic, the inscription increasingly difficult to read. It had appeared earlier still in a Board of Works publication of 1911 to 1912, documented by Robert Cochrane alongside ground plans and elevations of Glendalough's ecclesiastical remains.

Reefert Church itself sits in the upper valley at Glendalough, a little apart from the main monastic cluster, and the slab rests just outside its western wall. The inscription is not labelled or highlighted in any way on site. The best chance of seeing it clearly is in low, angled sunlight, which throws the shallow incisions into relief. It is worth moving around the slab rather than viewing it straight on, and worth knowing in advance what you are looking for.