Avoid a metal grinding wheel when you polish jade so that it doesn't break or chip -- especially if you're just starting out as a lapidary -- a person who cuts, carves, polishes or engraves stones and gems as a hobby or eventually a business.
Since you've taken the next step up from just being a rock hound, a thorough understanding of your equipment and processes to tumble or polish stones can mean the difference between success and failure. Once you understand the characteristics of jade, you'll have a better idea of how to turn this rough, ugly-looking, somewhat nondescript stone into a work of art.
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Only two types of jade are considered authentic: nephrite jade and jadeite jade. The Chinese have long cherished jade, carving it into weapons, ornaments, tools and artistic pieces. Mayans and Aztecs used jade for jewelry and religious artifacts and even for medicinal purposes. Before its rough exterior is polished and carved, jade may look like any other rock on the ground.
Some jade may have a gray outer casing hiding its emerald-like beauty. But not all jade is green. Jade is also lavender, orange, red, brown, black, white and gray. The highest quality jade is a translucent emerald green known as Imperial Jade.
Hardness and Polishing
On the Mohs scale of mineral hardness, jade runs about a 6.0, with diamonds a 10 and mineral talc at the bottom of the scale at a 1. While jade is a relatively medium-hard stone, jade with grains or lines running through it need to be cut and polished with the grain to avoid snapping or breaking it.
To polish jade, start by sanding and smoothing it against a polishing wheel. It takes time and experience to learn how much pressure to apply to the stone when holding it against the sanding material. Start with a light pressure and increase until you start to see the sanding action work.
Things You'll Need
120-, 300-, 600-grit wheels, drums, discs or belts
1,200- and 3,000-grit sanding wheels, drums, discs or belts
Aluminum marking stick
Leather or muslin buffing pads or belts
Attach the 120-grit wheel, drum, disc or belt to your polishing machine. The type of machine you have drives the sanding medium you attach to it.
Hold the jade against the wheel, moving the jade's direction at least 90 degrees every 10 to 15 seconds, which helps prevent gouges, chips or breaks. It also prevents undercutting of the stone.
Change the sanding material to the next grit level and repeat the process across the entire stone. Sand the stone in a pattern that resembles a zigzag stitch on a sewing machine to avoid cutting in too deeply on any one portion of the stone.
Repeat this process for each successive grade of sanding material over the entire surface of the stone, finishing up with the 1,200-grit material.
- Mark the piece of jade with an aluminum marking stick for each sanding material grade. When you have completely removed the aluminum marks, you can change the sanding material to the next grade.
- Lower quality jade stones develop an orange peel look no matter what you do.
- A chrome oxide polishing compound works best for jade; it's green and best for stones under cut.
Add a buffing pad matched to your polisher.
Apply the polishing compound to the stone -- whether a bar or paste-type product -- and hold it against the buffing pad, moving the stone in all directions until it's shiny.
- Always wear protective goggles, a face mask and gloves when polishing stones.
- Don't mix polishing pads and polishing compounds. Dedicate a polishing pad to each compound used.