Outdoor stairs in blasted stone.

[calle336]

Now I have finished roughly mortaring my outer stairs and boulders. Now the question is what final layer of plaster I should use. Should I continue with fine cement or should I go for plaster cement (type c-brick). I'm talking about the joints between the stones. They will have a height of about 1-5 cm and a width of around 1-5 cm.
Hoping for some good tips and advice
I have a picture on my phone but unfortunately cannot transfer it to the computer
Maybe I'll have time to fix it this evening.

Best regards, Calle

 

[calle336]

Some pictures

 

[calle336]

A follow-up question on this popular topic
Do you think you need to treat the joints somehow so they don't absorb moisture and then freeze and break?? Or is this not necessary?