Tutorial - Iota's Green Half-Pearl

As reported on the prop's Details page, Iota's left jewel has the every appearance of a pale green half-pearl, sized to be about 4.5mm in diameter:

As you're likely not going to find for your accurate Iota replica a ready source for this exact item, you'll have to make your own...

1. Purchase 4.5mm pearls - look for cultured freshwater pearls (sans drilled holes), since modern plastic pearls come only in whole millimeter (3mm, 4mm, 5mm, etc.) sizes. They're going to be shipped from overseas and take a while to arrive, so get at least ten to assure you end up with an adequate number of high quality to work on.

2. Pick out the best pearls. Find those that aren't terribly oblong, or have noticeable bumps or pits, as do remember these are products of nature. Divide them into your test batch and your production batch. Of course, try every new step on a "test" pearl first.

3. Roughen up the surface. To give the paint we're recommending the best chance of adhering (which is a challenge), roll the pearls around between your fingertip and a sheet of 600 grit sandpaper for about 20 seconds to lightly abrade the entire surface. This also takes the specular shine down somewhat, but that's good, as these raw, natural pearls actually start out too glossy.

4. Grind and sand the pearls to half-size. Pearls are nearly rock hard, so you'll first want to take off the bulk of material using a power tool - the Dremel 9903 cutter tip below worked best. Hold the pearls in smooth-jawed plyers (ridges will dig in, leaving dents) and do all your work above a tray or shallow box to catch the little buggers when you drop them, which will happen often. Once done with the machine trimming, push the flattened surface repeatedly with your finger across the full length of that 600 grit sandpaper (on every pass you'll lose about a hundredth of a millimeter) until you get the half-pearls to a height of about 2.06 mm. This is of course less than the 2.25 mm you might be expecting (half the optimal 4.5 mm pearl diameter), but the paint you'll be applying adds that extra bit. In terms of total work time, figure maybe about a half-hour per pearl, and if you're doing more than one, prepare for a sore fingertip by the end.

5. Color the half-pearl. The pearls' smooth nacre surface resists accepting pigments of nearly every type. Rit dyes barely absorb (even after months of soaking), Tamiya transparent spray paints go on mottled and can scrape right off, and the best HobbyLobby permanent markers brush on unevenly and wipe away too easily, with all primers and fixatives proving useless. But we did find one paint that's both durable enough and, with a little tweaking, looks incredibly spot on!

But first... the target color. Obviously the best screencaps to determine that are in Miri's "McCoy" close-up, though those frames have a slight blue cast that must be corrected for:

A representative area of our corrected aggregate jewel image was shrunk in Photoshop down to just a one pixel, which gives us the overall average hue:

The color saturation (how strong or weak the green is) and value (how black or white) were eyeballed.

This color call was then matched (under daylight comparison - ALWAY judge your pearl's coloring results under daylight, not artificial light) to a Benjamin Moore paint chip (found at Ace Hardware stores). Your aim is slightly lighter than their #2033-50, called "Bud Green":

We found the best paint type here are those used to simulate stained glass, since they're designed to be transparent and cling to non-porous surfaces. So here's what you'll need for this vital step:

To aid your manipulating ability here, temporarily afix your half pearls with glue stick to the top of small nails - the longer the better (for finger gripping), and with a head smaller than the pearl:

While several brands of stained glass paint exist, and they may all work, the one we know that does work is the Plaid "Gallery Glass." Their Kelly Green is wonderfully the exact right hue, though it's slightly too saturated straight out of the bottle, so the intensity needs to be diluted down. And their Clear Frost does that perfectly.

This paint starts out opaque, and at first you'll think you've got the wrong stuff. But once dried it becomes clear and reduces in volume, forming in essence a tough, green rubbery skin. Mix the (thick) Kelly Green with an equal amount of the (liquid) Clear Frost and stir thoroughly - though go slow as to not introduce more air bubbles than necessary; air bubbles look lousy dried on your pearl.

Dunk the entire half-pearl into the paint so that even the underside right up to the nail shaft gets coated. Once emersed, rotate the nail to give it all a uniform coating.

And if your paint coating doesn't come out smooth and even, it's easy enough to wipe it off with a paper towel and try again.

When you're satisfied with each, stick the nail upright into a firm foam base for drying, which takes about an hour:

Once dried, the paint develops a glossy outer surface (logical, given that it's meant to look like glass), so you'll need to knock that shine down. Way down. The best way to do that is to give your pearls multiple spray coatings of Rust-oleum "Frosted Glass," available at any hardware store:

Note that the above Styrofoam base was partially dissolved by the solvent in the spray. Lesson: don't use Styrofoam here. And be sure to spray this stuff outside or in a fully ventilated area, since this aerosol can also melt brain cells.

6. Remove the pearls from their nails. Don't just pry them apart, as the coating of paint that flowed around to the underside of the pearl is wholly connected to the paint on top, and some of that could rip off too. Rather, carefully shave off the nails with a knife, and then trim away any extra paint that still remains at the underside's edges. Fortunately the paint there is thin and cuts easily.

7. Clean the underside. Conclude the project by rubbing off any glue stick residue on the back with a damp paper towel.

And the sweet results...

From further back, Iota's control well must have looked about like this when new:

8. (Optional) Paint the underside white. This is listed as a "bonus" step because it adds just the smallest gain compared to the effort involved. As was mentioned prior, no color on the original jewel's underside is seen reflected off the hub in the "Miri" screencaps. However a bit of green will peek through the bottom of your half-pearl, which will reflect in the hub's chrome. It's not a big deal at this tiny scale, plus correcting this requires a deft touch and one fine-tipped brush to paint fully to the edges (with some Testors or acrylic model paint) while getting no trace of white on the green sides. Also, because paint in general doesn't stick well to the pearl, you'll then need to scrape off a patch of it from the center - exposing raw pearl surface - for the permanent glue to fasten the gem to its chromed hub. You decide if the work is worth it. (Note: the above finished photos show our pearl with this treatment):

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However, if in the end you don't like how a particular pearl turned out, the green paint will peel off clean with a gouging of your fingernail, and you can simply start over fresh:

p.s. We do not yet know how this coloring treatment will hold up over time. The only limitation the glass paint manufacturer states is that displaying the finished product in direct sunlight will cause eventual fading. If our sample pearls eventually show deterioration, maybe someone someday will update this tutorial, perhaps next trying the oven-hardened glass paint colors of Pebeo Vitrial.