Google has updated its Google Merchant Listings help documentation to add priceType property and then also give new sale pricing examples. Google said they did this to "make it easier for merchants to specify sale pricing through structured data and bring parity with price features in Merchant Center."
The new priceType property is priceSpecification.priceType or PriceTypeEnumeration. Google wrote:
Marks the full, original listing price of a product, if applicable. Only use this property if you want Google to show sale pricing for your product. You must set the priceType to the https://schema.org/ListPrice value (no other values are supported).If you use the priceType property to designate a list price, you must also provide a current sale price with the price or priceSpecification property. Don't mark the current sale price with the priceType property. See the sale price example.
Then Google added the Sale pricing examples and said, "The following example shows a product with a sale price. The current, offer price automatically becomes a sale price when you provide a second price with the original, list price and mark it with a priceType property of value https://schema.org/ListPrice. Don't mark the current, offer price with a priceType property."
Here is a screenshot of using this:
Alternatively, you can include two UnitPriceSpecification entries to specify the sale price and the list price, Google added:
Forum discussion at LinkedIn.
