result = list(transactions.values('customer').annotate(total=Sum('total'), gems=ArrayAgg('item', distinct=True)).order_by('-total')[:5])

    for item in result:
        sorted_gems = []

        for gem in item['gems']:
            for other in result:
                if other != item:
                    if gem in other['gems']:
                        sorted_gems.append(gem)
                        break

        item['gems'] = sorted_gems