Nine months of Smart Bidding trained on wishlist adds, not purchases

The situation

A UK luxury jewellery brand with pieces ranging from £800 to £12,000 had been running Google Smart Shopping for 9 months. Their campaigns spent £9,000/month and reported a steady stream of conversions. The founder was confused — the conversion volume looked reasonable but revenue from Google campaigns never seemed to match the spend.

The problem

A previous developer had accidentally set "Add to Wishlist" as the primary Google Ads conversion action instead of "Purchase." The jewellery website had a wishlist feature that customers used heavily — people saving pieces they wanted to show partners or return to later. Smart Bidding had 9 months of data teaching it to find people who save jewellery to wishlists. These people browse extensively and wishlist enthusiastically but convert to purchase at a very low rate, especially on high-ticket items.

What we did

1. Audited Google Ads conversion actions — found primary conversion: "Add to Wishlist" firing on wishlist button click
2. Checked GA4 linked conversions — "Purchase" event existed in GA4 but was imported as a secondary (non-bidding) action in Google Ads
3. Promoted Purchase to primary conversion action with transaction value included
4. Demoted "Add to Wishlist" to secondary informational signal only
5. Extended conversion window to 90 days — luxury jewellery consideration cycles regularly exceed 30 days for high-ticket pieces
6. Gave Smart Bidding 6-week learning period — purchase volume lower than wishlist but carrying real revenue signal

Why it worked

Luxury jewellery has one of the longest online consideration cycles of any ecommerce category — customers may research for weeks or months before purchasing a £3,000 piece. Setting "Add to Wishlist" as the primary conversion compounds this problem: Google finds efficient wishlist adders (browsers who never buy) rather than buyers who consider carefully and then commit. The 90-day conversion window is critical to capture the full research-to-purchase journey.