Mounting Vibrating Laps and Centrifugal Casting Machines
Q: I need to install a vibrating lap in a fixed location, so it won’t walk all over the place. Short of bolting it to the concrete floor, any ideas on how to stabilize the base?
Do I really Need the GRS Benchmate System?
Q: I’d like to get a GRS Benchmate system for supporting my work, but the budget’s not there. Are there any alternative setups that are nearly as useful as the Benchmate systems?
Drilling Wet with a Flexible Shaft Tool
Q: I’ve purchased a Foredom flexshaft, and I want to drill some holes in glass, which I’ve seen done using a shallow pan of water to contain the glass and cool it. Is this dangerous for the tool, and would I run the risk of electrocuting myself?
Is Carving Soapstone Dangerous?
Q: I’ve heard that some soapstones contain asbestos, and should be avoided by carvers. Then I heard that the soapstone itself was toxic, because it contains talc. Is this true?
Q: What is fossil ivory? Is it petrified? Can you carve it?
Q: I am interested in carving a piece of stone and was wondering if it can be done without a lot of fancy equipment.
Q: I have a large piece of black slate, ½ inch thick, that I’d like to use for a table top. What is the best way to cut, polish, and seal it.?
Q: Somebody told me that diamonds are hard, but not tough. Is this really true? Do I have to be especially careful when setting them?
Q: One of my clients is looking for a stone called “Krysokoll”. I think it is a Swedish word. Any idea what this stone is?
Diamonds vs. Cubic Zirconia
Q: How does one test a stone to see if it’s cubic zirconia (CZ) or a diamond?
Q: How on earth can you drill a hole in diamond? Isn’t it the hardest thing on earth? If it has something to do with diamonds being softer in some directions, how can you drill a hole, which goes all the way around?
Agate and Jasper
Q: What is agate? Is it the same as jasper?
Diamonds and What They are Worth
Q: How does one judge the quality of a diamond? What are the five C’s? Do I really need to spend two months salary on an engagement ring?
The Well-Cut Stone
Q: In a faceted gemstone, what characterizes a good or a bad cut? Can a transparent gem be set in a dark depression and still sparkle? Does it need light from the sides or bottom?
Tightening Prongs on a Setting
Q: How do you get the prongs of a Tiffany head to hold a stone tightly? And how can you clean up prongs without catching and distorting them?
Colored Stone Durability
Q: I want to make a set of rings with a range of colors from red to orange, yellow, green, blue, and purple. I know tourmaline comes in these colors, but is it durable enough to last? What else could I use without spending a fortune?
Lapidary Polishing Pads and Points
To start, it may help to describe what is probably the most common polishing process.
After the stone has been properly prepared for polishing by a series of sanding steps, the polishing compound, generally a metallic oxide in powder form, is mixed in a liquid, usually water, and applied to the polishing pad.
Obsidian is a volcanic glass which often contains attractive colors and inclusions, but has a reputation as being difficult to polish, although it is fairly soft and is usually uniform in structure. When people are having problems polishing obsidian, I find it is almost always because they didn’t get the sanding done adequately before attempting to polish.
Charoite is purple calcium potassium silicate. It is usually found combined with minerals of other colors, including black (Augerine Augite), orange (Tinaksite), and transparent crystals (Microcline Feldspar). Most Charoite comes from the countries of the former Soviet Union.
I have not found it to be very heat-sensitive.
Lapidary Polishing Pads and the Proper Speeds to Spin Them
Unfortunately there just isn’t one speed that works best. The glass industry has published a lot of research work on polishing glass and they found if you can keep everything else equal, the faster the surface contacting the glass runs, the faster the polish happens.
Rhodonite, an attractive pink and white gemstone, has a structure commonly called sugary: the material has small openings that will give an “orange-peel” surface that resembles badly polished jade. It is not the same thing, however. The orange-peel on jade comes from directional dissimilar hardness, or grain structure; the voids in rhodonite are actual holes and will not polish out.
I started researching jade polishing several years ago when I took over our club shop. I could get a polish on jade, but trying to tell someone else how to do it didn’t seem to work. What I found, when I started reading, was that most authors had the same problem I had: they could do it, but the ability to someone else was hard.
Lapidary Polishing Compounds
Everyone wants to know what the “best” polishing compound is and how it is used. Unfortunately I don’t think there is a single “best”—just a better one for the stone in question, depending on your technique. But here are some of my thoughts on the subject.
Nephrite and Asbestos
Nephrite is not asbestos. The confusion arises from the fact that nephrite has the same chemical composition as one of the forms of asbestos (Actinolite).
The characteristic of asbestos that causes trouble is its ability to easily break into fine fibers that are too small to be seen by the human eye.