Short answer. It depends on fault. If the seller was not at fault, the buyer bears the deterioration; if the seller was at fault, the buyer may instead choose between rescinding the sale or going through with it, with damages either way, since the seller is treated as the debtor of the obligation to deliver.
What the law says
In case of loss, deterioration or improvement of the thing before its delivery, the rules in article 1189 shall be observed, the vendor being considered the debtor.
Civil Code, Article 1538 — Loss/Improvement Before Delivery. Read the full provision →
The seller is treated as the debtor for this purpose
This article does not set its own separate rule for a sale — it borrows the rules of Article 1189, which normally govern obligations subject to a suspensive condition, and applies them to the period before delivery in a sale. It does so by treating the vendor as the debtor. That framing matters because Article 1189's rules assign consequences based on whether the debtor was at fault, and here the seller occupies that debtor role.
Deterioration without the seller's fault falls on the buyer
Under the borrowed rule, when the thing deteriorates without the fault of the debtor — here, the seller — the impairment is to be borne by the creditor, meaning the buyer. So if the deterioration happened through no fault of the seller before delivery, you as the buyer generally absorb that loss in value, receiving the thing in its deteriorated condition without automatically getting a price reduction.
Deterioration through the seller's fault gives the buyer a choice
Where the deterioration happens through the fault of the debtor — the seller — the rule shifts in the buyer's favor: the buyer may choose between rescission of the obligation and its fulfillment, with indemnity for damages in either case. This means a buyer facing a seller's fault is not stuck simply accepting the damaged item; the buyer can walk away from the sale or insist on going through with it, and either way can also recover damages for the loss in value.
Total loss is treated differently from mere deterioration
If the thing is completely lost rather than merely deteriorated — it perishes, goes out of commerce, or disappears so that its existence is unknown or it cannot be recovered — the borrowed rule provides that the obligation is extinguished if the loss happened without the seller's fault, but the seller must pay damages if the loss happened through the seller's fault. Whether your situation is a full loss or only a deterioration, or a partial destruction closer to one than the other, affects which of these specific outcomes actually applies.
Related provisions
- Civil Code, Article 1538 — Loss/Improvement Before Delivery
- Civil Code, Article 1189 — Loss, Deterioration, Improvement Pending a Suspensive Condition