Hi Maria,

Thank you for contacting Mearto with your appraisal inquiry.

I haven't found out the particulars about this outfit (it's too long to be a jacket and because it doesn't close below the waist seems inappropriate to call it a gown) or when actress Kate Chapman might have worn it. Nicole Grant is even more perplexing as she is not a well-known name and Google searches turn up nothing connected with NBC.
The "theatricality" of this outfit suggests it was once part of the studio's costume department and while some costumes for noteworthy productions can bring significant money (particularly at auction), without knowing more information about which production(s) this was made for and worn in, it's hard to justify a higher fair market value than $400-600.

Based on the photos and information provided, and subject to examination, this is:

A NBC Studio costume department multicolored synthetic satin costume
circa 2000
In vibrant blue, pink, green and yellow, with large shawl collar, ruffled decolletage and chevron bust, open from the waist down, with a long train, with a pink lining. Tagged with studio tags for "Nicole Grant" and "Kate Chapman".
Size: small
CONDITION: In good condition
PROVENANCE: Acquired in an online auction
$400-600*
*represents a fair-market value for auction purposes; retail or asking price may vary.

Please let us know if you have additional items to appraise, or questions/concerns, and thank you again for using Mearto.
~ Delia