On one dive, led by experienced Dutch guide Lerinde, we enter the water at the actually emerald-coloured "Blue Hole", close to the island's iconic "Azure Window" rock formation.
In form these early medieval windows varied considerably: the actual window openings were at first filled with thin sheets of marble, alabaster, gypsum, or even wooden boards, which were pierced with holes, coloured glass being inserted into these holes.
It was almost as if a Turner Prize-winning artist had been at the site 10 minutes before tipping coloured powders into the holes to make a metaphorical point about an artist and his/her palette, or a reflective pun on the term 'landscape painting'.
They begin by melting some solid coloured glass in the "glory hole" – the reheating chamber.
I climbed into disused piggeries with my friends and stared at walls stained rust-coloured with blood and at holes in the floor, where pigs were thrown after slaughter.
There's another dome-shaped cup, and four additional cups with Olympic ring-coloured rims, black lids with and without holes.
The bloodstains have faded but bullet holes remain etched in the peach-coloured wall where Mary Hawkes, a troubled 19-year-old, died in a blast of gunfire.
This mask contains about 200,000 precisely located holes, each accurately aligned with three different coloured phosphor dots on the screen in front of it.
This odd "space first" happened when northern flicker woodpeckers mistook the shuttle's external tank's reddish-coloured foam insulation for rotting wood and bored numerous holes in the foam.
Pearls, like some coloured stones, in ancient Classical times were pierced with a drill, the hole going half or all the way through according to whether the pearls were to be strung on a necklace or fastened onto a jewel.
