If a magus uses craft magic to create an item of beauty such as a fine painting, tapestry or finely crafted temple, what determines how beautiful it is?
Now if it wasn't craft magic and they did it the old fashioned way, then we'd just use perception (i'd guess) + relevant skill, say craft: mason for a statue. The craft skill we can assume covers the artistic talent as well.
Would we say that Finesse covers the same artistic talent? Finesse is after all a much more general skill.
And would it be perception as the appropriate paired characteristic?
If you're doing something physical with finesse, then it's usually at a difficulty modifier of (doing it with the regular skill) +3. Our group has house-ruled that if you have the regular ability (such as Mason), you can use that instead, at the regular difficulty level.
EDIT - although I believe the official rules are in the Jerbiton section of HoH:S - lemme go check.
EDIT II - yeah, HoH:S, pg. 60-61. It's Per+Finesse, with a +3 modifier.
The topic is also addressed in Art & Academe (page 132 onwards). That introduces a concept known as the Aesthetic Quality which determines how good an artwork is.
That has the Aesthetic quality from craft magic as being Int + Finesse, with a 3 point penalty (plus an extra penalty depending on how long an artist would take to create the artwork mundanely).
Looking at the crafting rules in City and guild, there are options for using better materials and innovative workshops to boost craft totals to enable the crafting of superior items. Now an innovative workshop is clearly irrelevant to rego craft magic. But would you allow a raw material bonus if the magus was working with materials better than normal. So for instance, would Carrara marble give a bonus to craft over bog-standard limestone? This seems sensible to me. It also allows rego craftsmen to edge towards being able to make the more exceptional items where the craft level required is otherwise too high.
Is there anything else that might boost those totals, other than very high int and finesse? Confidence point expenditure of course, but anything else?
Simply the virtue "Free Expression", it grants a +3 bonus for any original artistic endeavour, regardless of the skill used.
HoH:S lists various boni and mali for the use of Finesse, one of them being familiarity with what the mage is trying to do with Finesse (another +3 potential bonus). However, I would consider that if you are truly familiar with the topic you want to create, it might not qualify anymore for an original, work, thus preventing the +3 bonus from Free Expression.
It is up to debate.
My take is Finesse can be substituted for any craft skill, artistic or not and if used as Rego magic, without any virtus cost impact. Thus it should never be as easy to create master work as it would be for a mundane artist or craftsmen of high skill. And preventing staking of too many boni help keeps Craft magic under control.