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[ileney]

Hi,

I have quite a bit of Botswana agate, Queensland and other agate that shows parallax. Some pieces seem to show good parallax after I cut them, some not so much, but I am not following any particular rules to cutting and grinding. Are there any tips or rules to cutting/grinding/polishing to maximize the parallax?

[rocks2dust]

It is all going to depend on the piece you have. Generally, the best parallax is going to be in the 1 or 2 slices close to the center of the stone, and 90 degrees to the band pattern, assuming the center of the stone contains the core around which the banding wraps. In small stones, the banding is often going to curve so quickly that you won't be able to see down enough for a good effect. The agate between the bands needs to be very translucent (though I've seen some Botswana with white dots in there that didn't interfere too much), and the opaque bands need to be thin. If you can get a thick enough slab, some produce a better effect with higher domes.

[irockhound]

I love shadow agates.  The aussies at rough and tumble in Quartzsite had several barrels the last couple years and although you couldn't hand pick and had to buy by the scoop the material had very few duds.  So many shadow stones in that mix.  Rocks2dust is spot on and the basics are to just cut perpendicular to the bottom of the stone.  I have had a couple that were nice and long and the parallax ran down the stone so I was able to get several good slabs out.

If you have a stone that like most Botswana is already broken and you see the parallax you may have to trim or glue up the stone so that you can make your cuts so the parallax is perpendicular to the blade (think of an arrow sticking in the center of a target and the bands of the target going straight back).  If the angle of the parallax is off the effect is quite diminished.