vls2.30 on black granite photo

[sukhoi]

Hi from Bulgaria, sorry for my bad english ,
i have a ULS 2.30 30W laser and for now i am a dummy with engraving photo on black granite. But my granite is not 'assoluto nero'.
Attach two photos to show the results:
I use 2 inch lens and 250 dpi images.
for this photo i use 30% power, 50% speed and image density 3


for this photo i use 100% power and 70% speed and image density 5


If any have a vls 2.30 30W with more attempt than me, can you tell me the best settings for my laser
Thanks!

[sukhoi]

for first photo this is the link
Snimka.bg: 124 -
for second
Snimka.bg: 124 -
this photo is brushed with oil paint