Byzantine wall mosaic of the kind at San Vitale, Ravenna: gold glass tesserae set at slight tilts so the whole wall shimmers, a strictly frontal, elongated figure, large eyes, drapery drawn as lines. Furniture widens toward the back in what is called reverse perspective.
An icon is a window for contemplation, governed by canons rather than personal style, which is why saints became fixed portrait types after Iconoclasm ended in 843. Why the parallels diverge is still debated; the artists may simply not have had linear perspective to reject.
Every stone gets its own small gold gradient with hashed jitter, and a few are tilted to glint. The niche, border and ground band are cached once. The figure is drawn frontal and stretched ten percent, with fold lines and enlarged eyes. There is no halo and no disc: this is a donor, not a saint.
No halo, no cross, no Greek abbreviations. The figure stands where a donor would, not where Christ or a saint would.