Royal Canadian Mint-stamped gold wafer appears to be fake

Mint investigating after piece purchased by Ottawa jeweller Oct. 18 at Royal Bank of Canada branch.
http://www.cbc.ca/news/canada/ottawa/fake-gold-wafer-rbc-canadian-mint-1.4368801

The bar was purchased at the RBC branch at the corner of Bank Street and First Avenue for $1,680 on Oct. 18, by Samuel Tang, a gemologist and jewelry designer at the Joy Creations shop across the street.
Tang’s goldsmith, Dennis Barnard, said he opened the mint-branded packaging to roll the bar into a thin sheet for jewelry manufacturing. He immediately realized something was wrong when he started working with the metal.
“Visually, it was spot on. It was a phenomenal piece. Initially, holding it in my hand, I was fooled. The weight was spot on,” he said.
While the Canadian mint is assuring us this fake gold didn't come from them, (they are investigating) this is still quite troubling to the everyday gold buyer as we tend to keep it in its original packaging.

In light of this information, I have been looking for ways to test for fakes in the easiest and least intrusive ways.
The "ping" test seems to be the best and fastest identifier of fakes. As it turns out, there is also an app for this. http://www.cointrustapp.com/en/index.php

another easy test for jewellery

Step 1 Pour the white vinegar into your glass cup. Do not add water.
Step 2 Place the gold ring into the cup of white vinegar.
Step 3 Let the gold ring sit in the cup of white vinegar for approximately 15 minutes.
Step 4 Remove the gold ring and rinse with water. Real gold will shine while fake gold will change colors in reaction to the ascetic acid.
Other metals in contact with the vinegar begin to oxidize.
https://www.leaf.tv/articles/how-do-you-use-vinegar-to-find-out-if-a-ring-is-real-gold-or-not/

Silver ping test.

This method may scratch coins but is also a good identifier.