Verdict
Mayco Jungle Gems are worth buying if you fire low fire and want bright, busy crystal patterns that no plain glaze can give you. The jar holds a gloss base glaze plus small pieces of glass frit, and in a cone 06/05 firing those pieces melt and "burst into color," in Mayco's words. Mayco lists around fifty current colors in 4 oz jars and pints, plus a 12-jar assortment kit.
The limits are clear in Mayco's own material. Jungle Gems are for decorative use, the crystals settle in the jar and need constant stirring, and heavy crystals near the foot can stick to shelves and stilts. They are not a cone 6 glaze. This review is research-based: we compared Mayco's line page, product pages, 2024 low fire brochure, its crystal glaze Q&A and its discontinued color notices. We did not fire the glazes.
For where Jungle Gems sit among Mayco's other lines, see our Mayco glazes review.
Jungle Gems at a glance
| Spec | Mayco's figure | Source | What it means at home |
|---|---|---|---|
| Type | Crystal glaze: gloss base plus glass frit crystals | Line and product pages | Spotty, multicolor patterns, not flat color |
| Cone | Cone 06 to 05, 1,830°F to 1,915°F (999°C to 1,046°C); fire to shelf cone 06/05 | 2024 brochure | A low fire kiln or a cone 06 program |
| Coats | 1 coat translucent; 2 to 3 coats for full opacity | 2024 brochure | Brush two or three coats for all-over color |
| Brush | Soft fan, such as CB-604 #4 or CB-618 #8 | 2024 brochure | A fan lays crystals down evenly |
| Sizes | 4 oz and pint | Product pages | Try colors in 4 oz first |
| Kit | 12 x 4 oz assortment (also pints) | 2024 brochure | Cheapest way to see a range |
| Dinnerware | Decorative use; product pages show a not dinnerware safe icon | Brochure and product pages | Keep off food surfaces |
| Cone 6 | Crystals fade and melt; enhanced mobility; surface issues may occur | Product pages | Not a mid-fire glaze |
Price band: pints typically $17 to $23 at US dealers in October 2026, with 4 oz jars well below that. Check the live price.
How Jungle Gems make their crystals
A Jungle Gems jar is two things mixed together: a liquid gloss glaze and solid crystals of colored glass. When the kiln reaches cone 06, the crystals melt into spots, streaks and blooms of color inside the base glaze. Mayco says results vary with crystal size, the slope of the surface and the firing temperature.
This is different from crystalline glazes, which grow crystals during cooling. Jungle Gems carry their crystals in from the jar, so where you put them is where the color lands. That is why stirring and brush loading matter so much more than with a normal glaze.
Colors, the kit and what Mayco lists now
Mayco's current Jungle Gems color page runs from CG-718 Blue Caprice through CG1013 Papaya and beyond, with chips at cone 06, cone 6 and cone 10. The 12-jar assortment kit in the 2024 brochure contains these colors:
| Code | Name | Code | Name |
|---|---|---|---|
| CG-785 | Royal Fantasy | CG-717 | Pistachio |
| CG-756 | Firecracker | CG-974 | Bloomin' Blue |
| CG-965 | Mocha Marble | CG-780 | Mystic Jade |
| CG-718 | Blue Caprice | CG-970 | Masquerade |
| CG-964 | Kaleidoscope | CG-753 | Sassy Orange |
| CG-798 | Black Iris | CG-962 | Blue Azure |
Pistachio (CG-717) and Blue Azure (CG-962) are in the brochure's kit list but did not appear on Mayco's current Jungle Gems color page when we checked. The brochure also prints the same kit codes (CGKIT2 and CGKT2P) for both the Jungle Gems kit and the Crystalites kit. Check the kit label or ask the dealer which colors are inside before you buy.
Koi Pond and Blue Caprice
Two colors show how Mayco describes the line. CG-983 Koi Pond at cone 06 is "a translucent, bright blue base glaze with orange, yellow, and white crystals and small blue specks." CG-718 Blue Caprice is an opaque bright blue base with green, yellow and blue crystals. At cone 6 Mayco says both lose their crystals: the base remains or lightens, the crystals fade and melt, and the glaze moves more.
Discontinued Jungle Gems colors
Mayco discontinued these colors in all sizes in January 2025: CG-973 Alligator, CG-980 Coral Puff, CG-986 Smoke and Fire, CG-993 Lavender Sprigs and CG-994 Field and Flowers, plus the Crystalites color S-2703 Berryberry Pie. Earlier, from January 2023, it dropped CG-988 Fireflies, CG-989 Fruit Punch, CG-992 Mint Chip, CG-995 Foggy Mist and CG-996 Spring Rain. Leftover jars may still turn up at dealers, but you will not be able to reorder them.
Crystalites: the sister line
Mayco's brochure also includes Crystalites, with S-27xx codes such as S-2701 Peacock Eyes and S-2724 Lotus Blossom. Mayco's crystal glaze Q&A says the difference is that Crystalites have slightly larger crystals than Jungle Gems. Both sit in the same low fire brochure with the same handling notes, and Mayco's combinations page layers S-2724 Lotus Blossom over CG-722 Seawind.
How many coats of Jungle Gems, and how to apply them
Mayco's 2024 brochure is the current instruction: one coat gives a translucent finish, and each extra coat adds opacity, with two to three coats for full all-over coverage. An older Mayco Q&A said three coats over bisque. If you want the base color solid and the crystals dense, use three.
- Bisque fire the piece, then wipe it with a damp sponge.
- Shake the jar well before each coat. Mayco says to stir often because the crystals settle by weight.
- Load a soft fan brush and lay the glaze on in an even coat. If the crystals sink while you work, dip the brush to the bottom of the jar or shake it with the lid closed. Our pottery brushes guide covers fan brushes.
- Let each coat dry before the next. On the last coat, spread out any crystals that clumped.
- Keep the crystals light near the bottom of the piece, so they do not bloom onto the shelf or stilt.
- Fire to shelf cone 06/05.
- Store the jar upside down with the lid tight, as Mayco recommends, so crystals do not cake at the bottom.
Mayco also allows application to wet or leatherhard clay, limited to two coats including any design work, with an unglazed area left for outgassing. Its brochure then says to fire that greenware to cone 04, which does not match the cone 06/05 range printed above it. Test before relying on a single once-fired schedule.
Do Mayco Jungle Gems run?
At their intended cone 06/05, Mayco's caution is not a general run warning but the crystals: heavy crystals at the bottom of a piece can bloom and stick to shelves or stilts. That is why the foot area gets a lighter coat. If you fire on kiln stilts, keep the stilt points well clear of crystals.
Above the range, movement is the problem. At cone 6 Mayco's pages say "enhanced mobility" and "surface issues may occur," and the crystals melt away. Treat any Jungle Gems firing above cone 05 as a test, never as a production plan.
Jungle Gems on light and dark clay
Mayco fires its cone 06 chips flat in oxidation on white earthenware, and its cone 6 chips on white stoneware. It does not publish results on red clay. Because one coat is translucent, a thin coat over a dark body will look darker than the chip, while three coats move closer to Mayco's photos. A white earthenware clay gives the brightest colors and the closest match to the chart.
Layering Jungle Gems
Mayco publishes several named low fire combinations, all at cone 06 with two layers of base glaze and two layers of top glaze, dried between coats:
- S-2724 Lotus Blossom over CG-722 Seawind
- CG-1012 Haystack over CG-722 Seawind
- CG-1011 Frosted Berries over CG-722 Seawind
- CG-1010 Periwinkle Sky over CG-722 Seawind
- CG-1008 Blue Guppy over CG-722 Seawind
- CG-1007 Blueberry Bubblegum over CG-722 Seawind
- CG-1006 Purple Reign over CG-722 Seawind
Mayco also shows CG-1006 Purple Reign with SW-231 Lilac Speck at cone 6 and 10 in both orders, a special case on stoneware. Its Q&A gives two more methods: brush a crystal glaze as an accent over Stroke & Coat or Foundations, or put it under two to three coats of Stroke & Coat so the crystals push through as they bloom. See our Stroke & Coat review for that line.
Are Jungle Gems dinnerware safe?
No, by Mayco's own labeling. The 2024 brochure says "For decorative use only" and recommends crystal glazes for ornamental use on low fire earthenware. The product pages we checked show a not dinnerware safe icon. Mayco's Q&A explains that crystals can leave tiny surface cracks where food can collect, and suggests non-food areas such as the outside of a mug or a plate rim. Never rely on any glaze being food safe on your own pots without firing to the stated cone and testing.
The product pages we checked also show Mayco's ACMI AP seal. Mayco's brochure adds that CL labeled products are not for children 12 and under, so read each jar's label.
Jungle Gems vs Mayco Elements
Both lines fire at cone 06/05, but they work differently. Jungle Gems carry glass crystals that melt into spots of color. Mayco Elements are two-tone float glazes whose second color settles into texture. Choose Jungle Gems for color bursts on smooth surfaces and Elements for earthy surfaces on carved or textured ware.
What Jungle Gems do well
- Effects in one jar: base and crystals come premixed.
- Huge color range: around fifty current colors, plus Crystalites.
- Small sizes: 4 oz jars make testing cheap.
- Low fire friendly: made for cone 06/05, the range of many small home and school kilns.
Weak points
- Decorative only: no food surfaces.
- Crystals settle: constant stirring, and crystal density varies piece to piece.
- Shelf risk at the foot: heavy crystals can bloom onto shelves and stilts.
- Not for cone 6: crystals melt away and the glaze moves.
- Color churn: Mayco has dropped ten Jungle Gems colors since 2023.
Who should buy and who should skip
Buy Jungle Gems if you fire low fire, make ornaments, tiles, planters or display pieces, or run a paint-your-own studio where bold effects sell.
Skip them if you make dinnerware, fire only at cone 5 to 6, or want even, predictable color. Our low fire glazes guide covers steadier options.
Where to start: the assortment kit
The kit is picked because twelve 4 oz jars cost far less than twelve pints and show how differently the colors behave. Check the contents list on the box, as noted above.
- Contents: 12 x 4 oz (pint version also sold)
- Cone: 06/05
- Coats: 2 to 3 for full coverage
- Label: decorative use
Pros
- Twelve colors to test
- Small jars
- Good for classes
Cons
- Kit list may include colors not on the current chart
- Decorative only
Who should skip it: anyone who fires only at cone 6 or wants a food-surface glaze.
The brush Mayco names
Mayco's brochure names its CB-604 #4 soft fan for Jungle Gems. A soft, loose fan spreads crystals without dragging them into clumps.
- Type: #4 soft fan
- Use: brushing glaze over larger areas
Pros
- The brush Mayco recommends
- Low cost
Cons
- Small for very large pieces (Mayco also names the #8 CB-618)
Who should skip it: potters who already own a soft fan brush.
Alternatives
If you fire at cone 5 to 6, look at AMACO Cosmos for decorative crystals that grow in the firing, or Mayco's SW-156 Galaxy for a cone 6 crystal glaze with a dinnerware label. For classic crystals grown on a cooling schedule, read our crystalline glaze guide.
Safety notes
Read Mayco's SDS for the Jungle Gems line before use. Brush rather than spray. Wipe up spills with a damp sponge and never dry sweep glaze or clay dust, which contains silica. If you grind fused crystals off a shelf or stilt, wet it, wear eye protection and a NIOSH-approved respirator.
Sources: Mayco Jungle Gems line page; Mayco product pages CG-718 Blue Caprice and CG-983 Koi Pond; Mayco Jungle Gems low fire brochure (2024); Mayco "The Scoop on Mayco Crystal Glazes" Q&A (archive); Mayco Updates page (discontinued colors 2023 and 2025); Mayco glaze combinations page; dealer listings (The Ceramic Shop, Mayco Paint Store) for price band and older coat advice. Specs checked October 2026.