NRS 151.162

If the value of the gift is expressed in the instrument providing for the gift or grant, or in a writing of the decedent, or in an acknowledgment of the donee, that value must be used in the distribution and division of the estate. Otherwise, the gift or grant must be valued as of the time the donee came into possession or enjoyment of the property or as of the time of death of the decedent, whichever occurs first.