Question
I hope this is an easy question.  We're in the process of having a gunite pool installed by a very reputable company.  They just finished the tile and coping phase where our coping is OK Flagstone, and there is an accent portion of the perimeter of the pool described (and drawn) to us as "rock boulders" instaed of the coping.  We picked "moss rock" because we preferred the darker/reddish color.  The boulders we looked at in the showroom were roughly 1-2 ft tall by 2-3 ft wide, give or take a little in that range.  The section according to the drawing would use about 12 of those as a base, then smaller ones to bring it all together.  The guys game out and did it while we were at work.  What we came home to was more of a "rock" wall per say vs decorative "boulders."  The rocks where about 6-10 inches by 8-12 inches, and many more were obviously used that what would have been used w/ boulders.  It still looks good and we don't want them to knock it out and re-do, thus delaying completion, BUT...my question is...are an abundance of smaller rocks cheaper than purchasing boulders to cover the same area and grout together?  Should we call them out for cutting corners and cost for themselves and still charging us for what we expected?  I'm just curious, I know I can purchase 4 quarter carat diamonds for WAY cheaper than a 1 carat diamond (yeah...now you know I'm a woman asking...lol).  Do landscaping rcks vs boulders work the same way?  Do we need to ask for a supply/parts discount?  Any insight you can give me would be much appreciated.
Thank you,
Jana

Answer
This is interesting, but I think I can help you here.  
First off, boulder rocks are generally cheaper than any type of flagstone rock. It sounds like you got more of a wallstone quality rock.  
It can sometimes (Not always) be the opposite of diamonds. The smaller and thinner stones are more sought after than the larger pieces.
1 or 2 inch flagstone for a patio, cost more than a 4 to 6 inch variety of the same type of stone for a wall.
The demand is higher for patio quality then wall quality.
Moss rock is unique. It only occurs on the surface, so their is a limited supply. I was at a friends quarry to see this once. It fetches a higher price than regular boulders because of this.
The price of stones always depends on the Geology of the region, and what is readily quarried locally. Shipping makes up almost all the cost these day. (Very expensive importing rocks from other regions.)
Now to answer your question.
No. In fact, the labour (Canadian Spelling, ha) would actually go up. It would take them more time to put together the smaller stones than the larger ones thus costing them time and money.
The price difference would be offset by this fact more than anything else to consider.
The bigger the stones = the quicker the install, and less labour.
I am thinking that perhaps they were running short on this size of moss rock, and substituted?
However, they should have consulted with you before they did this.
In my opinion, that would be the professional thing to do.
Thanks for the question.
I hope I gave you a little more insight?
Have a great weekend and enjoy your pool, it sounds beautiful. Kevin