What test pattern did you use for the circular ones? That looks super-useful, but I’m not familiar with it!
Looks like Inca or Mayan, or maybe Apache.
This is the one, I kept the settings all as recommended in the vid and then only changed the power to get the best range of shading by upping or downing the power only.
Once I had those burned (only took a few) I identified the best result and then tried to adjust the speed to quicken the process and maintain that range of shading…but 2500/min (on my 20w output diode) is a great setting if there’s no time constraint.
I then repeat the process using a different mode and the result is a chart of go-to settings.
X and Y test grid is ok but for me its better using the circular range.
I learned a lot from that vid and dont do so much speed/power guesswork and also use line interval more.
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I started this Thread with an iCube 10w laser. I finally got around to doing a rock something with the SF-A9 40w machine.
My granddaughter had her birthday dinner at a Chinese resturant (NY). You know those little black rocks you lay the chopsticks on? I brought one home to mark up as a souvenir, to send back to her.
13 = 2500mm/m, 60% power, 1 pass, 254LPI, Air, Arial 8.67mm tall.
Text = 2000mm/m, 50%, 2 passes, air, ISO9 6.52mm tall.
The result was unexpected. Rarher than blasting a groove in the rock like before, it just melted and bubbled up. The engraving feels like 60 grit sandpaper.
The top image is the actual color.
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I’d say it’s from a lot of silica in the stone which vitrifies (turns to glass) when subjected to high heat. Here’s a pic of a small stone I did and got the same result … and interestingly those little magnets sitting on it stick to it weakly so there must also be some iron in it.
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Nice clean work and the vitrification works well with that stone and settings.
I don’t know if it’s been mentioned before, but geologists in the future will have serious problems justifying that, what are nothing more than experiments, are not the work of extraterrestrial beings.
But those rocks rocks (are cool) 
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I have a a friend who’s getting married in two weeks. I had an open offer to make something for them, and when I suggested a slate cheeseboard, that apparently hit the spot.
I made two of these, 300x200mm (12"x8"), on my fiber laser using my standard slate two-step process. (First step does the deep engrave; second step micro-vitrifies the surface to make it really pop when wet.)
(Slate cheeseboards are just rocks in special shapes, right?)
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Nice! Of course slate is rock. This is worth sharing in Finished Creations too!
I like the way the gaps in the letter’s for the curles in the ‘&’ to pass through give a 3d effect..thats nice.
When you say vitrified, I thought that always came out dark, the color you have there is great..Does it reflect well?
I’m totally focused on slate the last few weeks and trying to get it just right.
Do you pre-treat or after?
Really want to be able to manipulate the images to apply extra power so specific areas contrast and pop, but its a lot of time learnin image software and less burning.
That is the nature of doing images with a laser. It is hard to get good reproductions when you only have two colors: burned and not burned. 
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For Christmas I have been doing some things, one of them is a cheeseboard too.
When´s ready I’ll show it.
That´s a good example of “more simple the best”.
(Not what I have in mind for mines )
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Another user posted asking for settings to mark soapstone. Apparently not at all with a diode laser. Here is the posting…
The flag is very cool, well done.
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