Hi Yves,
The first (and arguably the most important) question is “What
‘value’ is she looking for?” Does she want to sell it? Does she want
to include it in her will and needs a value to make sure everything
works out right with the kids (and/or the taxes) when the time comes?
Does she want to insure it? These are important questions because
each different reason dictates a different value, sometimes very
different. If it has a T&Co, VC&A or Cartier logo, or an exclusive
artist’s, then it has a whole new dimension of difficulty added to
it’s valuation.
Of course the most common answer to that question is “I really don’t
care about all that, I just want to know what it’s worth.” I never
have figured out how to respond to that one, other than to tell them
how much we charge for an appraisal. What I really want to say is
“are you buyin’ another one or sellin’ this one?”
The truth about appraisals of jewelry like your friend has, is that
a detailed and accurate description is far more important than the
value assigned, for anything other than insurance that is. They use
the value only to set the premium and max payout. Any other use by
insurance companies usually relies on the description more than the
value too.
A good description should be able to tell anyone in the trade that
reads it how to value the jewelry for whatever their purpose might
be, regardless of the type of valuation assigned. A good appraisal
should also include decent quality photos, front and back, which are
also quite helpful to anyone relying on the appraisal, especially for
replacement or identification in the case of loss or theft.
She really needs to talk with an appraiser that is familiar with
older jewelry if the value she is looking for is for a specific
purpose and needs to be in writing. Or to an auction house if she
wants to sell it. If she doesn’t want to pay for an appraisal and
just wants to get a feel for what it might bring on the open market,
EBay is a good place to start looking for similar items for sale.
Then she could take it to a few places that specialize in estate and
period jewelry and see what’s for sale and then what she’s offered
for it. The differences I’m talking about will become very apparent,
very quickly.
For what it’s worth and from what I see in your photos, it looks to
me like both pieces are definitely worth getting a good, professional
appraisal.
That’s the closest to a valuation as you’re gonna get out of me for
no charge. 
Her best bet is to go to the National Association of Jewelry
Appraisers website - najaappraisers.com to find a qualified appraiser
in her area, assuming she’s in the US. Elsewhere, I’m not sure who to
call, but a bit of web surfing should take care of it; NAJA might
even be helpful there too.
Hope this is at least somewhat helpful.
Dave Phelps