Drilling through 50mm Indian stone : with anything larger than a toothpick

[ToughButterCup]

It's getting expensive now - any ideas how to do so without smashing the stone?

I need to fasten some fence baseplates  through capping stone ( Indian 'stone flags'  50mm 600 by 600) 

 

So far I've 

• used a 6mm SDS with hammer action - might as well have used a pick axe
• used it without hammer - I want to finish the job sometime this year
• splashed a bit of water on the slab - better but still iffy....

 

Ideas please .....

 

[BotusBuild]

Diamond drill bit?

 

https://www.screwfix.com/p/erbauer-hex-shank-diamond-tile-drill-bit-6mm-x-67mm/51908

[mistake_not]

Core drills are often diamond tipped if you want to drill a bit hole.