Post by joemojave on Oct 27, 2009 21:11:15 GMT -5
I was recently contacted asking how to cab a stone that you suspect shows asterism so that the star will be centered. Instead of replying in private, i think it makes more sense to post it in the public forum. I am not an expert in this field, but I have done my share of star stones and I think my method works pretty well. First of all, buy my product called StarGazer <shameless plug>. To find the general direction of the star on the rough place 3 drops of StarGazer on the rough at 90 degrees to each other. Put the first one on the flattest face you can find and check for asterism by looking at the bead of liquid from all angles in the sun, then put the next one on an adjacet face, and the next one on a face adjacent to the first two. When you see the star in one of the drops, start playing with the drop with a needle or something until the star is perfectly centered with the light coming over your shoulder. Then draw extensions of each ray from the edge of the bead in fine point sharpy. Wipe of the StarGazer and extend the lines all the way across so that they form a star. The point at which these lines intersect should be at the center of the cab, with the strongest ray going either horizontal or vertical, if the cab is an oval.
Now that you have found the star, you need to decide how you want your cab to be shaped. Simple rounds are the best, but if one leg is much stronger than the others ovals are better. In any case the star you marked should be at the exact center of the cab which will be the highest point in the dome when the cab is finished.
After you decide on the form of your cab, it is time to rough it out. This works best on a very true flat lap IME because the stones tend to be very small and you never need to make concave edges which would require a grinding wheel. The first step in cutting the stone is to cut the back perfectly flat and perfectly perpandicular to the marks you made. Dont dop the stone yet because that makes it difficult to see the lines you drew. If you are confident in your skills in cabbing star stones, you can also break the corner around the bottom of the cab and polish the bottom, but if this is your first time cabbing a star stone then wait until later to do this.
Once the back is cut you can dop the cab. I like to use a drop of superglue and a nail because these stones are often small, but use whatever you prefer. Once the stone is dopped, cut the girdle. If you are making a circular cab, put the dop stick in a drill and then lightly kiss the lap with it until the high spots are ground out. Otherwise, just make it as symmetrical as possible and go to the next step.
After you have cut the girdle, take it of the dop using acetone or by freezing the stone and snaping the dop off. Use a girdle marker to mark where to cut the dome and then re-dop the stone.
Now just cut a fairly high dome and try to make it as symetrical as possible. When the dome is roughed out, dry it off and rub a drop of StarGazer onto the stone. Whallah, instand polish that will not evaporate. Now take the stone into the sun and see how well the star is centered. If this is your first time, chances are it wont be. If it is centered, continue to polish the stone and be finished. If not, re shape the dome so that it is centered and then re cut the back to be perpandicular to the dome. This is why you didnt polish the back at the begining: You probably needed to re cut it at this step and it would have been a waist of time.
When you get the star centered, polish up the stone and set it in a bezel and enjoy having your very own star ruby, quartz, or whatever.
You can buy 2oz bottles of stargazer from me for 3.50 plus shipping. PM me fore details or see my thread "End of the month garage sale (Freebies, to!)" in the selling section.
</shameless plug>
Now that you have found the star, you need to decide how you want your cab to be shaped. Simple rounds are the best, but if one leg is much stronger than the others ovals are better. In any case the star you marked should be at the exact center of the cab which will be the highest point in the dome when the cab is finished.
After you decide on the form of your cab, it is time to rough it out. This works best on a very true flat lap IME because the stones tend to be very small and you never need to make concave edges which would require a grinding wheel. The first step in cutting the stone is to cut the back perfectly flat and perfectly perpandicular to the marks you made. Dont dop the stone yet because that makes it difficult to see the lines you drew. If you are confident in your skills in cabbing star stones, you can also break the corner around the bottom of the cab and polish the bottom, but if this is your first time cabbing a star stone then wait until later to do this.
Once the back is cut you can dop the cab. I like to use a drop of superglue and a nail because these stones are often small, but use whatever you prefer. Once the stone is dopped, cut the girdle. If you are making a circular cab, put the dop stick in a drill and then lightly kiss the lap with it until the high spots are ground out. Otherwise, just make it as symmetrical as possible and go to the next step.
After you have cut the girdle, take it of the dop using acetone or by freezing the stone and snaping the dop off. Use a girdle marker to mark where to cut the dome and then re-dop the stone.
Now just cut a fairly high dome and try to make it as symetrical as possible. When the dome is roughed out, dry it off and rub a drop of StarGazer onto the stone. Whallah, instand polish that will not evaporate. Now take the stone into the sun and see how well the star is centered. If this is your first time, chances are it wont be. If it is centered, continue to polish the stone and be finished. If not, re shape the dome so that it is centered and then re cut the back to be perpandicular to the dome. This is why you didnt polish the back at the begining: You probably needed to re cut it at this step and it would have been a waist of time.
When you get the star centered, polish up the stone and set it in a bezel and enjoy having your very own star ruby, quartz, or whatever.
You can buy 2oz bottles of stargazer from me for 3.50 plus shipping. PM me fore details or see my thread "End of the month garage sale (Freebies, to!)" in the selling section.
</shameless plug>