(IDEX Online) - Plunging lab grown prices mean some brides-to-be are now embarrassed by the size of their engagement ring, according to the Wall Street Journal (WSJ).Rocks of two, three or more carats are becoming more and more common, leaving couples with a dilemma. Do they pretend they have the funds to buy a huge natural diamond, or admit it's a lab grown.The average retail price for a one-carat lab-grown is now $1,426, according to Tenoris data. A like-for-like natural diamond is almost four times the price, at $5,426.Esther Hare, a former triathlete, told the WSJ she upgraded from the original half-carat stone from her husband 25 years ago to a 4.5-carat oval-shaped lab grown that cost $40,000."A lot of times I won't take it on vacation because it's just a monster," she said.Bride Tiffany Buchert, 40, said her now-husband proposed with a two-carat lab-grown engagement ring. She hated it and they traded it in for a one-carat mined diamond - at twice the price.