Silver signifies 25 years of marriage, while gold signifies 50 years of marriage. According to Wedding Anniversary Gifts, Ideas and Suggestions, your 40th wedding anniversary is considered your ruby wedding and should be celebrated with a ruby theme. When choosing your ruby wedding cake, you have a myriad of options.
In order to keep with the ruby theme of a 40th wedding anniversary, you should pick a red-coloured cake. Red velvet cake will gives you a deep, dark red, while strawberry- or cherry-flavoured cake will give you a lighter, pinkish shade of red. If you aren't fans of those flavours, you can always use red food colouring to turn a white or yellow cake batter red. You can also make the outside of your cake ruby coloured by dying the frosting red.
If you decide on a multiple layered cake to celebrate 40 years of marriage, you can use a red fruit filling between the layers. You have your choice between strawberries, cherries or raspberry preserves.
You can show homage to the tradition of a ruby wedding by the shape of your cake. You could honour you first wedding by copying the design of that cake, use a traditional round tiered wedding cake or you could have your cake in the shape of a 4 and a 0. If you're baking your ruby wedding cake yourself and creating number shapes surpassing your baking skills, you could also bake cupcakes and place them so they read the number 40.
Flowers make a beautiful adornment to any wedding cake. Both nasturtiums and roses are associated with the ruby wedding anniversary, so decorate your cake with edible sugar or fondant nasturtiums or roses.
Since rubies are the traditional gift for the 40th wedding anniversary, why not put them on your cake? These gems can be spun out of sugar to add glamour and sparkle to your cake while remaining completely edible.