Dictionary.com
definitions

gold-plating

[gohld-pley-ting]

noun

the incorporation of costly and unnecessary features or refinements into a product or structure.
any expensive nonessential item, convenience, or feature: an apartment with a sauna and other gold-plating.

Origin of gold-plating

First recorded in 1960–65

gold-plate

[gohld-pleyt]

verb (used with object), gold-plat·ed, gold-plat·ing.

to coat (base metal) with gold, especially by electroplating.
to incorporate costly features or refinements into (something) unnecessarily: The engineers were accused of gold-plating the construction project.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for gold-plating

gold-plate

verb

(tr) to coat (other metal) with gold, usually by electroplating
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012