The Crystal Crafter's Compatibility Chart
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Which stones survive resin, sunlight, water, heat and a sander — and what each piece actually costs you. Six printable pages with sources on the page, written for makers who sell what they make.
For resin artists, charm makers and market sellers
The Crystal Crafter's
Compatibility Chart
Which stones survive resin, sunlight, water, heat and a sander — and what each piece actually costs you. Six pages, sourced, printable, and written for someone who sells what they make.
Stone by stone
| Stone | Mohs | Resin | Sun | Water | Dry sanding | Verdict |
|---|---|---|---|---|---|---|
| Clear quartz | 7 | Vanishes | Stable | Fine | Silica | Let points stand proud; it disappears when submerged |
| Amethyst | 7 | Good | Fades | Fine | Silica | Great in resin, wrong for a sunny window |
| Rose quartz | 7 | Good | Stable | Fine | Silica | The “rose quartz fades” rule is a myth (GIA) |
| Citrine (heat-treated) | 7 | Good | Fades | Fine | Silica | Nearly all citrine is heated amethyst. Label it |
| Smoky quartz | 7 | Good | Can lighten | Fine | Silica | Colour is irradiation-based; strong sun dulls it |
| Black tourmaline | 7–7.5 | Excellent | Stable | Fine | Wet-cut | The safest dark stone for anything outdoors |
| Obsidian | 5–5.5 | Excellent | Stable | Fine | Sharp | Volcanic glass — gloves when sorting chips |
| Agate / carnelian | 6.5–7 | Excellent | Stable | Fine | Silica | Slices are the workhorse of coasters and hangings |
| Dyed agate | 6.5–7 | Excellent | Dye fades | Fine | Silica | The stone is stable; the dye is not. Keep indoors |
| Jasper | 6.5–7 | Excellent | Stable | Fine | Silica | Opaque, cheap, forgiving — ideal beginner stone |
Stone by stone, continued
| Stone | Mohs | Resin | Sun | Water | Dry sanding | Verdict |
|---|---|---|---|---|---|---|
| Tiger's eye | 7 | Good | Stable | Fine | High hazard | Never dry-grind. Fibrous dust |
| Hematite | 5.5–6.5 | Good | Stable | Keep dry | Wet-cut | Surface can spot in standing water |
| Labradorite | 6–6.5 | Good | Stable | Fine | Cleaves | Angle it to the surface or you lose the flash |
| Lapis lazuli | 5–6 | Seal first | Stable | Brief only | Wet-cut | Porous — it will bubble if you skip the seal coat |
| Fluorite | 4 | Shallow pours | Some fade | Never soak | Cleaves | Slightly soluble; dark colours lighten from ~100 °C |
| Malachite | 3.5–4 | Stunning | Stable | Avoid | Copper dust | Beautiful, and the one stone never to dry-sand |
| Howlite (often dyed) | 3.5 | Very porous | Dye fades | Porous | Soft | Sold as “turquoise” everywhere. Say what it is |
| Angelite | 3.5 | Good | Stable | Converts | Soft | It is anhydrite; water changes the mineral itself |
| Selenite / satin spar | 2 | Sealed only | Stable | Dissolves | Scratches | ~2 g/L soluble. Never in anything that meets a wet glass |
| Pyrite | 6–6.5 | Good | Stable | Corrodes | Wet-cut | Seal it fully or it weeps and stains over time |
Sources: Mohs values from standard gemmological references. Fade behaviour: GIA care guidance for amethyst, citrine, rose quartz and kunzite; International Gem Society for fluorite. Solubility: gypsum ≈2–2.5 g/L at 25 °C. Dust hazards: OSHA and the US National Cancer Institute on respirable crystalline silica; IGS gemstone toxicity table for copper- and fibre-bearing stones.
Choose by what you are making
| You are making | Use | Avoid | The reason |
|---|---|---|---|
| Resin coasters & trays | Agate slices, jasper, quartz, obsidian | Selenite, fluorite, howlite | It is the wettest thing you sell. Assume a sweating glass |
| Geode-style resin art | Crushed mini chips, dyed agate, druzy | Clear quartz alone | Clear stone vanishes against clear resin — you need contrast |
| Keychains & bag charms | Tumbles, tiny chips, jasper, tourmaline | Soft stones under Mohs 5 | A keychain lives in a pocket with keys. Hardness is the whole spec |
| Suncatchers & window pieces | Clear quartz points, natural agate, tourmaline | Amethyst, citrine, fluorite, dyed stone | Direct sun for months is the harshest test in this list |
| Spell jars & bottles | Tiny chips, 15–30 g a jar | Selenite or halite if anything wet goes in | Soluble minerals disappear and cloud the jar |
| Candle tops | Quartz chips, jasper, agate | Selenite, malachite, anything coated | Stone is not flammable, but heat cracks soft and treated stone |
| Wall art & mosaic decor | Anything — it is dry and indoors | Nothing in particular | The one format with almost no constraints |
| Bookmarks & flat pieces | Chips and small slices | Chunky or heavy stone | Weight is what snaps thin resin |
Chip grade to project
| Grade | Size | Pieces per kg | Best for |
|---|---|---|---|
| Crushed mini | Sand to 3 mm | Thousands | Geode fill, inlay, jar layers, sparkle |
| Tiny | 2–10 mm | 150–240 | Spell jars, small resin work, fill |
| X-Small | 3 mm–1 in | 100–160 | Keychains, charms, scattered resin |
| Small | 0.5–2 in | 50–100 | Wrapped pendants, focal chips, trays |
| Medium | 1–2 in | 20–50 | Statement pieces, branch wands, decor |
| Large | 1.5–3 in | 8–20 | Display pieces, one-offs |
Piece counts are approximate and vary with density — hematite, pyrite and garnet run heavier, so a kilo holds fewer pieces.
Cost per finished piece
The number that ends the pricing argument. Fill it in once per stone you use.
| Stone & grade | Bag price | Pieces (or grams) | Cost per piece | Used in |
|---|---|---|---|---|
Worked example
A 1 kg bag of tiny chips at a listed $20 holds roughly 200 pieces — about 10 cents of stone per piece. A resin keychain using a pinch of chips carries maybe 30 cents of stone. If that keychain sells for $18, materials are not your problem. Labour and markup are.
Five things that go wrong, and why
1 · The clear stone disappeared
Quartz has a refractive index of about 1.544–1.553. Cured epoxy sits around 1.55–1.60. When two materials bend light almost identically, the boundary between them stops being visible — so a clear quartz point submerged in clear resin optically vanishes. It is physics, not a bad batch. Fix: use coloured or opaque stone, tint the resin, or let the point stand proud of the surface.
2 · Everything sank to the bottom
Stone is far denser than resin, so a single pour will always settle. Fix: pour a base layer, let it gel until it is tacky, place the stone, then pour over it. Two thin layers beat one thick one for every reason on this page.
3 · Bubbles came up overnight
Porous stone holds air and releases it once covered. Druzy, geode, lava, howlite, turquoise and lapis are the usual offenders. Fix: brush a thin seal coat over the stone, let it go tack-free, then embed.
4 · The resin cured cloudy
Moisture is the most common cause, and damp inclusions are the most-missed source of it. Fix: wash chips, then dry them completely — not “mostly”. Keep moulds and tools dry too.
5 · The UV resin stayed soft underneath
UV light travels in straight lines. Anything in the shadow of an opaque chip never cures. Fix: cure in thin layers, flip and rotate, or switch to two-part epoxy for anything with depth.
The dust page
Handling stone is not the hazard. Making dust from it is, and almost nobody in this craft says so out loud.
- Quartz-family stones (quartz, amethyst, agate, jasper, tiger's eye) release respirable crystalline silica when cut, ground or sanded dry. OSHA links it to silicosis, lung cancer and COPD, and the IARC classes it as a Group 1 carcinogen.
- Malachite and azurite add copper to the dust and are rated high hazard by the International Gem Society for exactly that reason.
- Tiger's eye is worse again — fibrous material plus silica.
- Finished, polished pieces are not the hazard. Nothing on a market table is dangerous to hold, wear or sell. It is the workshop step that needs the control.
Pricing, briefly
| Step | What goes in | Yours |
|---|---|---|
| Materials | Stone (from page 4) + resin + mould wear + packaging | |
| Labour | Your real hourly rate × the time, including cure-day handling | |
| Overhead | Table fees, fuel, cards, the share of your supplies that got wasted | |
| Subtotal | Add the three | |
| Retail | Subtotal × 2.2 to 3.0 (craft-fair convention) | |
| Wholesale | Half of retail, if a shop wants to stock you |
Reality check from craft-fair guidance: impulse items sell best between $10 and $40, and a set of four resin coasters typically retails $25–$40. If your maths lands far outside those bands, the product is wrong for the venue — not the price.
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