Wondering wether you have the common silver Welsh harlequins or the more rare gold Welsh harlequins? It's a common question here on BYC, hopefully I can help you out a little.
Before we proceed I would like to note that silver is not a recognized variety in the UK, therefore when I say "silver" and "common" please understand that it's because I'm an American.
My goal here is not to explain the science of their color but to simply show you the visual difference between the two, and the different ways to figure out which is which.
SPECULUM!
Yup! That pretty sparkly patch on their wings is a surefire way to tell a silver apart from a gold!
Gold: They have a greenish or plain bronze shimmer on their speculum, as pictured below. (Notice the lack of black?)
Silver: Their speculum has a dazzling blue or bright purplish green shimmer to it and is significantly brighter than gold speculum.
Speculum is the most accurate way to tell them apart. While you're looking so closely at the wing go ahead and examine those dark wing feathers. Silvers will have black feathers here, while the golds will have dark brown.
Side note: I took these photos in the evening with the "flash" on. Having light to reflect the colors makes it easier for positive identification.
Other ways to tell?
Got some flighty ducks? Can't tell what color that speculum is? Don't worry I've been there. There are still some easy ways to tell em apart.
1. Baby fuzz.
Not only is it cute, it's useful too! Baby silvers are yellow with grayish shading on those little heads and tails. Golds are yellow with a brown shade on their head and tails. Baby fuzz isn't super accurate but it works! Make sure you're not trying to determine their baby fuzz color while they're under the heat lamp, use white light or sunshine.
2. Drake tail feathers.
Since the proper welsh harlequin drake has a dark tail laced with white, their tails can be very tell-tail (hehe, get it? I said tail because we're talking about his tail! Okay, I'll stop now). A silver drake will have a smokey black tail, while the gold variety has bronze on those tail feathers.
Looking for how to tell drakes apart from hens in the first place? Here's a great article by cheezenwhackers!
What gender is my duck?
3 . Overall appearance.
From left to right: Silver drake, Gold hen, Silver hen.
It's an easy but less accurate way to tell them apart. Silvers have a very striking "black and white" look, though some will be extremely fawn. Golds tend to be one of two extremes: very light (almost completely white) or very fawn (almost brown), they're more muted overall.
Welsh harlequins are known for becoming darker with age, so knowing your duck's age will be important when trying to determine color phase based off of looks alone.
References:
Dave Holderread wrote a fantastic book on raising ducks. I am constantly referring to it, I highly recommend adding it to your poultry library!
Storey's Guide to Raising Ducks
I hope this was helpful, thank you for taking the time to read this! Good luck with your welshies! They're my absolute favorite breed. Regardless of their color phase, welshies are adorable, sparkly and sweet.