The industry has spent a decade selling deep-vein leaves as the premium standard: heavy, dramatic ridges pressed deep into the plastic, visible from across the room. Hold a real olive leaf up to the light and the veins sit a tenth of a millimetre proud of the surface. Faux leaves that carve vein channels deeper than half a millimetre are not trying to be leaves. They are showing you the mould.

The 0.3 mm line: where leaves end and moulds begin

Measure the underside of the leaf with a feeler gauge, not the eye. Real veins are a two-part structure: a midrib of 0.2 to 0.3 mm and secondary veins under 0.15 mm, spaced 8 to 12 mm apart, getting finer toward the tip. Every leaf in a healthy bunch varies. The leaf that sells realism is the one where the relief is barely there and the spacing is never the same twice.

Deep relief betrays the part it is hiding. Under raking light at 10 to 20 degrees, a vein channel deeper than 0.3 mm casts a hard-edged shadow. Real leaves cast a soft gradient: the ridge is small enough that the shadow blurs before it lands. That shadow line is what your eye reads as plastic, long before you touch anything. It is the same failure as the 70 GU gloss line, in a different dimension: the surface speaks about the object before the object speaks.

Why the deep vein gets made anyway

Because it is cheaper to make and harder to kill. A deep feature demoulds cleanly from the injection tool, hides the weld line, and shrugs off the crush-and-reset cycle of shipping. Printed veins – digital ink laid flat on a PVC skin – solve the relief problem by deleting it: 0.0 mm of depth, flat under a fingernail, and the ink starts fading under 280 nm UV long before the base does. The market split into two bad answers: carved too deep, or printed flat. Neither is a leaf.

The three tests that sort real from moulded

First, the fingernail drag. Run a fingernail across the underside of the leaf, midrib to edge. You want to feel a gradient. If the nail catches on a groove, the relief is past 0.3 mm and the leaf will read fake under any light you own.

Second, the shadow width. Rake a single lamp across the leaf at 10 to 20 degrees and look at the vein shadow, not the vein. A shadow edge under 1 mm wide with a soft transition passes. A hard edge is a mould channel, and no matting or wash will fix what the light exposes.

Third, the two-part check. Vein areas should sit at the same or lower gloss than the leaf base – the midrib of a real leaf is duller than the lamina. If the veins read shinier than the rest of the leaf, you are holding a two-part mould where the vein insert was painted separately, and the finish will track different. That is the leaf-level cousin of the 70 GU failure.

The spec to buy to

Write it down and send it: midrib relief under 0.3 mm, secondary veins under 0.15 mm, spacing variable between 8 and 12 mm, matte surface at 30 to 50 GU, PE leaf on PE stem over PVC. PE takes a shallower, finer vein and holds it; PVC wants depth and gives you the hard shadow. For QC, pull ten leaves per lot, gauge the midrib on all ten, and reject any lot where four in ten sit above 0.3 mm. One lot, ten minutes, and the whole category of fake reads you have been explaining to buyers disappears.

The leaf never fails on shape. It fails on relief. Put the vein under the 0.3 mm line, keep the surface under 70 GU, and the plastic stops announcing itself – at 0.2 mm the vein is a whisper, and that is exactly where a real leaf lives.