For carving Pakistan Green Onyx with CNC milling tools, I recommend using diamond-coated milling bits or end mills specifically designed for stone carving. Given the small diameters you mentioned (0.8mm-2mm), you should look for micro-tools with diamond coatings.

Here are a few recommendations you can consider:

1. Diamond Coated Ball Nose End Mill: This type of end mill is suitable for carving and contouring intricate shapes in stone. The ball nose design allows for smooth carving and reduces the chances of chipping or damaging the material.

2. Diamond Coated Engraving Bit: These bits have a sharp point and work well for engraving fine details and intricate designs. They are available in various diameters, so you can select the size that suits your requirements.

3. Diamond Coated Burrs: Burrs are versatile tools that can be used for carving, engraving, and shaping stone. Their small size makes them perfect for intricate work. Look for burrs with diamond coatings to ensure longevity and durability.

It is essential to choose high-quality tools that are specifically designed for carving stone, as they will ensure clean cuts and reduce the chances of damaging the material. Additionally, consider the spindle speed and feed rate when operating the CNC machine to avoid overheating or putting excess pressure on the delicate milling bits.

Please note that the mentioned tool types and diameters are recommendations, and your specific carving requirements may differ. It is always recommended to consult with your CNC machine manufacturer or tool supplier for personalized recommendations based on your project needs.