I can't believe we're still talking about this.

I am not worried about your visual reference at the top of the spring.
It's what you say you're doing at the bottom ....... that you are either doing it wrong, or describing it wrong.

If there is a spring seat/shim between the spring and the head, and you're putting the caliper down against the head..... you're doing it wrong........period.
Doing it that way does not account for the thickness of the seat.
The caliper needs to be on top of the seat.........or you need to know how thick it is and subtract that from your measurement if you're measuring down to the head.

I'm not there watching you do it, so I can only go by what you say........ and you say you're putting the tool down against the head.........and when you do that you get 1.885.
The seats are usually .060....... so if you subtract the thickness of the seat from your measurement of 1.885.......the installed height should be 1.825...... based on how you say you're doing it.

Do you have a solid lifter adjusted to zero lash(or at least a bottomed out hyd lifter)when you're visually checking for space between the coils?