Cutting the table

[Pro-oz]

When cutting the crown, at what point does everyone cut the table? I have been leaving it until last as per the cutting instructions, but a lot of the time my meat points don't match up, (some before the other)

Is there a better way? I know my 45deg. adapter is out can adjust to that and not a problem. I have had the quill modified by VJ faceting machines, and now that hasn't got the runout the old one had.

At the moment cutting and cutting the crown fist instead of the pavilion first, to see if that's more accurate, in case of transfer problems. I have a new VJ transfer jig, it's simple design but seems pretty good.

I have a Hall Mk-3 machine, have modified it to variable speed, instead of flicking a belt over. Much better to use now.

So, on closing any tips would be very much apricated.

Cheers for now,
Pro-oz

[Faceting Frank]

 I cut the table last as per instructions and have the 45 deg dop set with the hard stop on my machine. I use an ink marker on the 45 deg dop surface to set its height and cheater setting before fitting the stone dop. So, I’m cutting the table with the hard stop and looking for any required adjustments as it cuts.
I find it near impossible to get all the meet points with the crown perfect Pro-oz. If it’s a round stone cutting all the star facets to the same depth will keep their adjacent meets the same. This will probably mean altering below facets to fix any meets that are out before cutting the table. I find this very accurate and only a 10x loupe will spot any meet point errors. Other shapes like ovals will most likely have 4-star facets at one angle and 4 at another angle. Same again keeping each set of four the same depth of cut will keep the meet points consistent.
You don’t need to bother about any alignment on your machine, just use the hard stop and the cheater to keep the meet points equal as your cutting.

[Pro-oz]

Thank you, Frank, for your reply. Just finished the crown and table on one of MB design, a round stone Nonastar Brilliant out of volume 5, which has 9 meats for the table. This one I cut the crown first as a trial and very happy with it, not perfect for a comp cut, but have to have a very hard look with a 10x loupe to see the meet point errors.

This stone a Topaz, is showing it might have a lot of sparkle, very clean clear stone.
Thanks Frank have taken your advice on board. At least I know I'm on the right track. A bit more time yet and may have a go at a competition cut.

Cheers,
Pro-oz  (Peter)

[Faceting Frank]

The Gemboree comp is a good place to start, they should be putting their 2026 comp details on their website next month. https://aflaca.org.au/gemboree/. They even put cuts like a standard round brilliant in the open section. So, if you have not entered their comp before, you could enter stones in all sections at once. I’ve seen a few people put stones in both the intermediate and open sections, they also allow two entries with each cut.

[Faceting Frank]

The Gemboree have just published their 2026 comp stones Pro-oz and a lot more natural material in all sections than they usually have. Tourmaline, amethyst, sapphire, ametrine, topaz, quartz, zircon and Citrine. CZ being the only man made stone.

[Pro-oz]

Thank you I'll have a look.

Cheers

[Pro-oz]

Might order some CZ and have a go. Better get the table right haha.

[mehoose]

Good heavens Frank... A sapph finishing in at 6mm  .. what would the rough cost for that these days?

[Faceting Frank]

Not cheap mehoose. 
I found a weight to size chart for gemstones on the net. A 6mm round sapphire would weigh just over 1ct, the average return for a commercial cutter from a piece of rough is 20%. Will need a piece of flawless rough big enough to guarantee the finished stone is well over 6mm diameter.

[steve f]

I just finished a sapphire 8.4mm and 4 carats on the dot

[Faceting Frank]

Thats a big sapphire steve f. If you don't mind me asking how big was the rough and how much did it cost you?

[steve f]

25.5 cts $660 about four years ago, it had a crack through the middle of it so I cut on the crack-line so I still have half of it to cut when I get better at cutting
First half was practice

[mehoose]

Not cheap mehoose. 
I found a weight to size chart for gemstones on the net. A 6mm round sapphire would weigh just over 1ct, the average return for a commercial cutter from a piece of rough is 20%. Will need a piece of flawless rough big enough to guarantee the finished stone is well over 6mm diameter.

that's going to be pricey comp to enter this time around. I mean, finished gem needs to be flawless doesn't it.. or you lose points? Or have I got the wrong end of the stick?

[Faceting Frank]

Yes, your right mehoose, pricey for sure and it's 3 points for flaws. I've cut topaz stones in the past that had faint flaws in them that only showed up after polishing the pavilion, so had to cut another one. Have asked BR Gemstones for a price on a sapphire of around 8ct and a 10ct tourmaline, will have to wait and see what they come up with. If I do cut those stones, I'm not going to bother with flaws that can't be seen with the naked eye, got to maintain as much weight as possible.