Need way more information and more specific questions. Pictures etc.

My question is would it be okay to mix exterior brick skirting with a limestone rock replace interior with the same color tone of both skirting and fireplace. Using dark gray siding. Pictures are included in my first post.

Fireplace (not replace)

The photo of the brick fireplace is very pretty. But for outside with a dark gray siding, I would choose something that has grey in it. There has to be some kind of stone foundation that fits your budget. They’re all veneers.

Is the price difference that big?

IMO we need to see the exterior and also why you need to have brick there at all.

I am undecided between white and dark gray

I am leaning towards the white.

No brick or stone on the exterior of that farmhouse-style home. It's not appropriate for the design. However, if you'd like to use something at the base of the columns that would be OK.

Cover the block with paint and foundation plantings.

I agree with Beverly. The brick foundation skirting wouldn't fit that style home. If it's in a woodsy setting, maybe a river rock style that could also be extended to hardscape in your front yard in the form of raised beds or retaining walls.

Something like the rock in this outdoor fireplace. Don't know whether it's more expensive than brick (probably), but it might be worth it:

Clump Rock · More Info

Jennifer, do a search for foundation veneers. My friends are residing their house and needed something at the base.

There are tons of options in a variety of stones - round, stacked, small, large. And you can get either white or dark gray/black to blend in with the house. No need to paint.

Remember, foundation plantings will cover this part of your house too.