A crystal ball is a polished sphere on a stand, and the first useful thing to know is that most of them are glass rather than quartz. Neither is dishonest as long as it is stated — but they cost very different amounts and behave differently in the hand.
Telling glass from quartz
Three tests, none of which needs equipment.
- Bubbles. Round bubbles mean glass. Natural quartz has veils, feathers and angular inclusions, but not neat spherical bubbles.
- Temperature. Quartz feels colder against the lip or cheek and stays cold longer. Glass warms to your hand quickly.
- Perfection. A completely flawless, water-clear large sphere at a modest price is glass. Flawless natural quartz at 100mm is genuinely rare and priced accordingly.
Good glass spheres are lovely objects and there is nothing wrong with buying one knowingly. The problem is only ever the label.
The sun warning, which is not folklore
A sphere is a lens. A crystal ball on a sunny windowsill will focus sunlight to a point hot enough to scorch wood and ignite paper or fabric, and as the sun moves that point tracks across whatever is nearby. Fire services in several countries issue warnings about it every summer.
Keep it out of direct sun, or on a stand well back from the window. This is the one piece of advice on this page that actually matters.
Sizes in practice
Under 60mm is a desk object. 80–100mm is the size most people picture. Above 150mm the weight becomes serious — quartz is about 2.65 times the density of water, so a 200mm quartz sphere is around 11kg and needs furniture that can take it.
Scrying, briefly and honestly
Scrying is gazing into a reflective or translucent surface until the mind produces imagery. The tradition is old and cross-cultural — water, mirrors, ink, polished obsidian — and what is happening is a well-documented perceptual effect: with a featureless visual field the brain begins to supply pattern. Whether you read that as psychological or as something else is your business. It is not a claim we need to settle in order to sell a nice sphere.